EP4658073A1 - Use of dimpropyridaz for reducing or preventing bacterial transmission - Google Patents

Abstract

The invention relates to the use of dimpropyridaz for reducing or preventing bacteria transmission from insect vectors to plants, and to methods for reducing or preventing bacteria transmission from insect vectors to plants by applying dimpropyridaz.

Description

Use of dimpropyridaz for reducing or preventing bacterial transmission

Description

The invention relates to the use of dimpropyridaz for reducing or preventing bacterial transmission from insect vectors to plants and protecting plants from bacterial diseases.

1-[(1RS)-1,2-dimethylpropyl]-N-ethyl-5-methyl-N-pyridazin-4-yl-1H-pyrazole-4-carboxamide of formula I: is known from WO 2012/143317. This compound is mentioned to be useful for combating a broad variety of invertebrate pests. It is known under the common name dimpropyridaz.

Vectors are organisms that can introduce a pathogen, such as a virus or bacteria, into a plant, by feeding to cause an infection. Such insect vectors include, for example, hemipteran, thysanopteran and acari species such as aphids, whiteflies, leafhoppers, planthoppers, treehoppers, thrips, mites, scales, mealybugs, spittlebugs, froghoppers, plant lice, and psyllids, which also cause direct feeding damage to plants. Disease transmission from vectors to plants is a widespread cause of plant damage, for which there are only few effective measures of control.

Up to now, the only effective means for reducing bacterial infections transmitted by vectors is the control of the vectors, e.g., by using insecticides, which stops infestation before it happens. The use of antibiotics in agriculture is not commonly accepted because of its selective activity against only certain bacteria, as well as the nature of use, which can be only curative, once the disease is already present, and overarching implication to human health and antibiotic resistance.

Insecticides alone or in mixtures with other known pesticides, which may be used for reducing infections transmitted by vectors (insects), are known. However, the effectiveness of these insecticides or insecticidal mixtures in terms of reducing disease transmission from insect vectors to plants is not always satisfactory.

This is because the insect vectors are often capable of transmitting the disease before the insecticides kill them. It is important to note that, as insect vectors, such as hemipteran insects like aphids, whiteflies, leafhoppers (in particular Cicadellidae) and planthoppers (in particular Cixiidae) move through a plant and briefly probe, by time the insect receives a lethal dose of the insecticide, pathogen transmission will often be completed, and the damage already done. Thus, there is also a need for insecticides, which not only kill the insect vectors, but primarily cause a quick feeding cessation in insect vectors, which enables the reduction or cessation of the vector’s ability to acquire and transmit the pathogen before the plant is infected. This quick feeding cessation in insect vectors by an appropriate insecticide not only helps in reducing the severity of disease on affected plants, but also helps in reducing the spread of disease to other plants in the field. Hence, there is a need for insecticides, which effectively reduce or cease the ability of insect vectors to transmit the disease causing pathogen.

We have found that this need is met by the application of dimpropyridaz to the plant.

Furthermore, it has been observed that some insecticides agitate the insects and encourage greater movement and feeding, resulting in increased rates of bacterial spread. Therefore, there is also a need for insecticides, which inhibit movement and/or feeding of the insect vectors before killing them. We have found that this need is met by application of dimpropyridaz to the crop.

It is further generally desired to reduce dosage rates of insecticides, and therefore also in connection with combating insect vectors. Accordingly, there is also a need for insecticides, which can be applied in lower doses than conventional insecticides. We have found that this need is met by application of dimpropyridaz to the crop.

It is therefore the object of the invention to provide an insecticide which satisfies any of the above needs. Surprisingly, it has been found that dimpropyridaz is suitable for reducing or preventing bacteria transmission from insect vectors to plants. Dimpropyridaz controls insect vectors, particularly whiteflies, aphids, leafhoppers, and planthoppers (e.g. Cixiidae like Pentastiridius sp.) in all development stages.

Accordingly, the invention relates to the use of dimpropyridaz or a stereoisomer, tautomer, salt, or N-oxide thereof, for reducing or preventing bacteria transmission from insect vectors to plants. The invention further relates to a method for reducing or preventing bacteria transmission from insect vectors to plants comprising the step of contacting the plants, parts thereof, their propagation material, the insects, their food supply, habitat, or breeding ground with a pesticidally effective amount of dimpropyridaz or a stereoisomer, tautomer, salt or N- oxide thereof. All embodiments and preferences described throughout this document are both valid for the use and the method of use aspect of the invention.

The remarks made as to the preferred embodiments of the use or method of the invention are to be understood as preferred on their own as well as preferably in combination with each other.

As used herein, the term "pathogen" includes bacteria, such as phytoplasma.

As used herein, the term "bacteria transmission from insect vectors to plants" refers to the introduction of a pathogens into a plant to cause an infection. Such transmission is typically characterized by the acquisition time, i.e. the time required by the insect vector to acquire the pathogen, the inoculation time, i.e. the time required by infectious insect vectors to infect the plant, the latent period, i.e. the minimum time between acquisition of a pathogen and ability of the insect vector to transmit the pathogen, and the retention time, i.e. the time after acquisition that an insect vector remains capable of transmitting the bacteria. As a consequence of reducing bacteria transmission from insect vectors to plants, insect-vectored bacterial infections of plants in a field can be reduced. Primary spread of the pathogens, i.e., the initial spread of the pathogen into a field by infectious insect vectors from sources outside the filed, and/or secondary spread of the pathogen, i.e., the spread of the pathogen within a field via acquisition of the pathogen by insect vectors from sources of the pathogens within the field and spread of the pathogen by these afterwards infectious insect vectors, may be reduced.

As used herein, the term "bacteria-infected" or "bacterial infection" in connection with plants means that the plant has been infected with a bacterium. As outlined above, bacterial infection is typically caused by inoculation by an infectious insect vector. Bacteria transmission from insect vectors to plants typically causes bacterial infections.

The term "plant" refers to multicellular photosynthetic eukaryotic life-forms belonging to kingdom Plantae including crops.

The term "crop" refers to plants grown for food or other commercial purposes. The application of dimpropyridaz to crops is a preferred embodiment of the invention. The application of dimpropyridaz to sugar beet or potato crops is a particularly preferred embodiment of the invention. In one embodiment, the crop is a sugar beet crop.

As used herein, the term "infectious insect vector" refers to an insect vector, which has acquired a bacterium and can transmit the bacterium, which means that the latent period is already over, but the retention time is not yet over.

Insect vectors in the invention are preferably Auchenorrhyncha, such as Fulgoromorpha and Cicadomorpha, particularly of the families Cixiidae and Cicadellidae, and more preferably of the Amarasca, Apartus, Circulifer, Cixius, Dalbulus, Empoasca, Hyalesthes, Myndus, Pentastiridius, Reptalus, Scaphoideus, Tachycixius, and Trigonocranus genera.

As used herein, the term "non-infected" in connection with plants means that the plant is healthy, i.e., not bacteria-infected. "Non-infected plants" may also be referred to as "bacteria- free plants". Dimpropyridaz is preferably used in fields comprising exclusively non-infected plants focusing on the reduction or prevention of primary spread of bacteria or in fields comprising bacteria-infected and non-infected plants focussing on the reduction or prevention of secondary spread of the bacteria.

As used herein, the term "non-infectious" in connection with an insect vector means that the insect vector is not capable of transmitting a bacteria, preferably that the insect vector has not even acquired a bacteria.

The term "contacting" includes both direct contact (applying the compound/compositions directly on the animal pest or plant - typically to the foliage, stem, or roots of the plant) and indirect contact (applying the compound/compositions to the locus i.e., habitat, breeding ground, plant, seed, soil, area, material, or environment in which a pest is growing or may grow, of the animal pest or plant). Maximal contact pertains to the application of dimpropyridaz to the pest and plant jointly.

"Pesticidally effective amount" means the amount of active ingredient needed to achieve an observable effect on growth, including the effects of necrosis, feeding cessation, death, retardation, prevention, and removal, destruction, or otherwise diminishing the occurrence and activity of the target organism. A pesticidally effective amount of the compositions will also vary according to the prevailing conditions e.g., desired pesticidal effect and duration, weather, target species, locus, mode of application.

"Reducing bacteria transmission” means a reduction of the number of infected plants by at least 50%, or 65%, preferably 80%, particularly 90%, or 95% compared to untreated control.

"Preventing bacteria transmission” means a reduction of the number of infected plants by at least 90%, preferably at least 95%, more preferably at least 99%, especially preferably by 100% compared to untreated control.

Although dimpropyridaz itself and its combined application with other insecticides are known to have shown activity against insect pests, it has not yet been known for solving bacteria caused problems in plants; especially sugar beet, potato, strawberry plants, and olive trees as mentioned above.

Salts of dimpropyridaz are preferably agriculturally and veterinarily acceptable salts. Such salts and their preparation are in general known from WO 2012/143317. Dimpropyridaz can be used in the form of its N-oxides. Its N-oxides are in general known from WO 2012/143317.

Dimpropyridaz may be amorphous or may exist in one or more different crystalline states (polymorphs) which may have different macroscopic properties such as stability or show different biological properties such as activity. The invention includes the use of both amorphous and crystalline compounds, their enantiomers or diastereomers, mixtures of different crystalline states of dimpropyridaz, its enantiomers or diastereomers, as well as amorphous or crystalline salts thereof. In one embodiment, dimpropyridaz is in the crystalline form described and claimed in W02020144308, especially as disclosed in Examples 1-4.

Dimpropyridaz is suitable for reducing or preventing transmission of pathogens from insect vectors to plants. Dimpropyridaz is particular suitable for efficiently controlling and preventing the transmission of pathogens by Auchenorrhyncha vectors. Auchenorrhyncha and the transmitted bacterial diseases caused by the vector entail severe damage in diverse crop cultures, such as sugar beet, potatoes, strawberry plants, vegetables, grapes, and olive trees, particularly in sugar beet and potatoes. Dimpropyridaz treatment is especially useful against the Cixiidae and Cicadellidae families. The planthoppers Cixiidae are a family of insects in the order Hemiptera (true bugs). They are in the suborder Auchenorrhyncha, along with smaller jumping bugs such as leafhoppers (family Cicadellidae) and froghoppers or spittlebugs (superfamily Cercopoidea).

The suborder Auchenorrhyncha contains the Infraorders Fulgoromorpha and Cicadomorpha. Examples of insects vectors within the Auchenorrhyncha suborder are of genera Apartus, Cixius, Hyalesthes, Myndus, Pentastiridius, Reptalus, Tachycixius, and Trigonocranus. In one embodiment, the insect vectors are Cicadomorpha insects. In another embodiment, the insect vectors are Membracoidea. In another embodiment, the insect vectors are Cicadellidae insects. In another embodiment, the insect vectors are Dalbulus insects. In one embodiment, the insect vectors are Fulgoromorpha insects. In another embodiment, the insect vectors are Cixiidae insects. In another embodiment, the insect vectors are Pentastiridius insects. In a preferred embodiment, the insect vectors are reed glass-winged Pentastiridius leporinus. In another embodiment, the insect vectors are Apartus michalki. In another embodiment, the insect vectors are Cixius alpestris. In another embodiment, the insect vectors are Cixius beieri. In another embodiment, the insect vectors are Cixius cambricus. In another embodiment, the insect vectors are Cixius cunicularius. In another embodiment, the insect vectors are Cixius distinguendusAn another embodiment, the insect vectors are Cixius dubius. In another embodiment, the insect vectors are Cixius heydenii. In another embodiment, the insect vectors are Cixius nervosus. In another embodiment, the insect vectors are Cixius similis. In another embodiment, the insect vectors are Cixius simplex. In another embodiment, the insect vectors are Cixius sticticus. In another embodiment, the insect vectors are Cixius stigmaticus. In another embodiment, the insect vectors are Cixius wagneri. In another embodiment, the insect vectors are Hyalesthes luteipes. In another embodiment, the insect vectors are Hyalesthes obsoletus. In another embodiment, the insect vectors are Hyalesthes philesakis. In another embodiment, the insect vectors are Myndus musivus. In another embodiment, the insect vectors are Pentastiridius beieri. In another embodiment, the insect vectors are Reptalus cuspidatus. In another embodiment, the insect vectors are Reptalus panzeri. In another embodiment, the insect vectors are Reptalus quinquecostatus. In another embodiment, the insect vectors are Tachycixius pilosus. In another embodiment, the insect vectors are Tachycixius venustulus. In another embodiment, the insect vectors are Trigonocranus emmeae. In another embodiment, the insect vectors are Glassy winged sharpshooter (Homalodisca vitripennis). In another embodiment, the insect vectors are Dalbulus maidis. In another embodiment, the insect vectors are Amrasca biguttula. In another embodiment, the insect vectors are Emporasca sp.. In another embodiment, the insect vectors are Scapohideus titanus.

It has been found that dimpropyridaz is suitable for reducing or preventing bacteria transmission from insect vectors to lots of crops, including but not limited to, potato, sugar beet, grapes, and strawberry plants. Dimpropyridaz controls Auchenorrhyncha vectors, particularly Fulgoromorpha like Pentastiridius leporinus and Cixius wagneri, as well as Cicadomorpha like Homalodisca vitripennis in all development stages. In one embodiment, the insect vector is selected from aphids, whiteflies, leafhoppers, thrips, psyllids, scales, mealybugs, planthoppers (e.g. Cixiidae) and mites, and is preferably selected from the group of aphids, whiteflies, leafhoppers, planthoppers (e.g.C/x/7'dae) and thrips, more preferably selected from aphids, whiteflies, Cixiidae and thrips, and is particularly selected from the group of Cixiidae, aphids and whiteflies, for example Pentastiridius.

In another embodiment, the insect vector is selected from Cixiidae and leafhoppers, and is preferably selected from the group of Apartus, Cixius, Hyalesthes, Myndus, Pentastiridius, Reptalus, Tachycixius, and Trigonocranus., more preferably selected from Pentastiridius spp., and is particularly Pentastiridius leporinus.

In particular, bacteria may be spread by Auchenorrhyncha which are one or more of e.g. Pentastiridius leporinus (Cixiidae), beet leafhopper (Circulifertenullus), and Agalliana ensigera. Plants exhibiting Auchenorrhyncha or aphid damage can have a variety of symptoms, such as decreased growth rates, mottled leaves, sooty mold growth as secondary infection due to to honeydew production, yellowing, stunted growth, curled leaves, browning, wilting, low yields and death.

The removal of sap creates a lack of vigor in the plant. Furthermore, Auchenorrhyncha frequently transmit disease-causing organisms like bacteria to their hosts through feeding. Similarly, whitefly and Cixiidae nymphs and adults feed by inserting their proboscises into the leaf, penetrating the phloem and withdrawing sap. It is during this feeding process that plant pathogens are acquired and transmitted. Particularly, adult whiteflies and Cixiidae may disperse and transmit the bacteria to new plants while feeding. Whiteflies, which represent bacterial vectors, include whiteflies in the genera Bemisia and Trialeurodes. A particularly important species of the genera Bemisia includes B. tabaci. Important species of the genera Trialeurodes include T. vaporariorum, T. abutilonea, and T. ricini. Whiteflies (Bemisia tabaci). Whitefly often infect tomato, eggplants, tobacco, beans and peppers, whereas Cixiidae and Cicadellidae often infect potatoes, and sugar beet. In another particularly preferred embodiment of the invention, the whitefly insect vector is therefore selected from the group consisting of B. tabaci, T. vaporariorum, T. abutilonea, and T. ricini, particularly the whitefly insect vector is B. tabaci. In another particularly preferred embodiment of the invention, the vector is therefore Pentastiridius leporinus.

Bacteria may be also be spread by psyllids such as Asian Citrus Psyllid (Diaphorina citri). The Asian Citrus Psyllid mainly causes bacterial disease (Citrus Greening, or Huanglongbing (HLB) disease).

Corn leafhopper (Dalbulus maidis) mainly causes bacterial diseases (corn stunt spiroplasma (CSS) and Maize bushy stunt phytoplasma (MBSP).

S. titanus transmits Flavescence doree phytoplasmas (FDp) causing FD grapevines or Grapevine Yellows (GY) and Pentastiridius leporinus spreads basses richesses syndrome (SBR) and Circulifer tenellus can spread phytoplasma/spiroplasma citri causing curly top. The reed glass-winged Pentastiridius leporinus mainly causes bacterial disease Basses Richesses (SBR) disease to Beta vulgaris ssp. sugar beet. Sugar beet plants exhibiting SBR can have a variety of symptoms, such as a general yellowing of the blows, lanceolate young leaves, and visible necrotic discoloration in the area of the vascular bundle rings.

The SBR disease is caused by the bacterium Candidatus Arsenophonus phytopathogenicus, and stolbur phytoplasma, syn. Candidatus phytoplama solani (stolbur) which are transmitted by the reed glass-winged Pentastiridius leporinus to the beets. The first symptoms on the sugar beet become visible at the end of summer. Older leaves show yellowing between the leaf veins. Newly sprouting leaves are very light to chlorotic and lanceolate. In most SBR-infested sugar beets, the beet body shows browning of the vascular bundles as well as a glassy and translucent parenchymal tissue. As a serious consequence of the disease, the sugar content of beets decreases significantly, and the sugar leaves also extract worse. Accordingly, in one embodiment the bacteria are Stolbur phytoplasma.

The reed glass-winged Pentastiridius leporinus also causes bacterial disease SBR to potatoes. It is. characterized by side shoots, wilting and rubbery tubers.

Marginal chlorosis of strawberry is caused by gammaproteobacteria in the Arsenophonus clade The disease-causing agents are Candidatus Phlomobacter fragariae which is transmitted by ciixid planthoppers (Cixius wagneri). Symptoms include little-leaf, proliferation, malformation of fruits, and marginal chlorosis of leaves.

The meadow froghopper Homalodisca vitripennis mainly causes Olive quick decline syndrome (OQDS) disease to olive trees. OQDS is a wasting disease of olive trees which causes dieback of the leaves, twigs and branches so that the trees no longer produce crops of olives. The main cause is a strain of the bacterium, Xylella fastidiosa, which is spread by plant-sucking insects such as the meadow froghopper. The bacteria restrict the flow of sap within the tree and so choke its extremities. Symptoms include leaf scorch and desiccation of twigs and branches, beginning at the upper part of the crown and then moving to the rest of the tree, which acquires a burned look.

Likewise, dimpropyridaz is useful for preventing or reducing the transmission of bacteria by the following insect vectors: Acyrthosiphum pisum, Aphis citricola, Aphis craccivora, Aphis fabae, Aphis frangulae, Aphis glycines, Aphis gossypii, Aphis nasturtii, Aphis pomi, Aphis spiraecola, Aulacorthum solani, Brachycaudus helichrysi, Brevicoryne brassicae, Diuraphis noxia, Dysaphis devecta, Dysaphis plantag inea, Eriosoma lanigerum, Hyalopterus pruni, Lipaphis erysimi, Macrosiphum avenae, Macrosiphum euphorbiae, Macrosiphum rosae, Myzus cerasi, Myzus nicotianae, Myzus persicae, Nasonovia ribisnigri, Pemphigus bursarius, Phorodon humuli, Rhopalosiphum insertum Wa, Rhopalosiphum maidis, Rhopalosiphum padi, Schizaphis graminum, Sitobion avenae, Toxoptera aurantii, Toxoptera citricola, Phylloxera vitifoliae, Bemisia tabaci, Nilaparvata lugens, Sogatella furcifera, Laodelphax spp, Nephotettix spp., Trialeurodes vaporariorum, Thrips tabaci, Thrips palmi, Bactericera cockerelli, Dalbulus maidis, Frankliniella schultzei, Frankliniella occidentalis, Pentasturidus leporinus, Circulifer tenellus, grapevine leafhopper: Scaphoideus titanus and Diaphorina citri. One aspect of the invention relates to a method for controlling Auchenorrhyncha, preferably Fulgoromorpha, especially Cixiidae and in particular, Pentastiridius leporinus, comprising the step of contacting the plant, parts of it, its propagation material, the insects, their food supply, habitat or breeding grounds with a pesticidally effective amount of dimpropyridaz.

For effectively controlling insects in potato, sugar beet, vegetable, grape, or strawberry fields, or olive trees, e.g. by foliar application, the rate of application of the active ingredients of this invention may be in the range of 0.01 g to 500 g per hectare, e.g. from 1 g to 300 g per hectare or from 1 g to 175 g per hectare, desirably from 1 g to 100 g per hectare.

In particular, it has been shown that primary and secondary spread of bacteria by insect vectors, can effectively be reduced or prevented by application of dimpropyridaz. On the one hand, it has been found that bacteria infected vectors that land on a dimpropyridaz-treated plant will exhibit a reduced ability of the vector to transmit the bacteria. On the other hand, it has been found that non-infected insect vectors, which land on a dimpropyridaz-treated infected plant, will have a reduced ability to transmit the bacteria to adjacent healthy plants.

Therefore, in one aspect, the invention relates to the use of dimpropyridaz for reducing or preventing bacteria transmission from insect vectors to plants.

In another aspect, the invention relates to a method for reducing or preventing transmission from insect vectors to plants, which method comprises applying dimpropyridaz to the insect vectors, crops, plants, plant propagation materials such as seeds, or soil or water, in which the plants are growing. One embodiment of the invention relates to the use of dimpropyridaz for reducing or preventing secondary spread. In another aspect, the invention relates to a method of protecting plants from bacterial diseases which method comprises applying dimpropyridaz to the non-infected crops, plants, plant propagation materials, such as seeds, or soil or water, in which the plants are growing.

In one embodiment, the invention relates to the use or method for reducing or preventing transmission from insect vectors to plants, such as sugar beet or potato plants, which use a method comprised of applying a pesticidally effective amount of dimpropyridaz, or a stereoisomer, tautomer, salt, or N-oxide thereof to the plant.

In another embodiment, the invention relates to the use or method for reducing or preventing transmission from insect vectors to strawberry plants or olive trees, which use a method comprised of applying a pesticidally effective amount of dimpropyridaz, or a stereoisomer, tautomer, salt, or N-oxide thereof to the respective plant.

In another embodiment, the invention relates to the use or method for reducing or preventing transmission from insect vectors to corn or citrus plants, which use a method comprised of applying a pesticidally effective amount of dimpropyridaz, or a stereoisomer, tautomer, salt, or N-oxide thereof to the respective plant.

In one preferred embodiment of the use or method of the invention, dimpropyridaz is applied to fields of non-infected plants, i.e. , fields which exclusively comprise non-infected plants, i.e. , do not contain any bacteria infected plants. As a consequence, primary spread of the bacteria can be reduced or even prevented as dimpropyridaz would prevent or significantly reduce feeding (transmission) of present and incoming insect vectors.

In another preferred embodiment of the use or method of the invention, dimpropyridaz is applied to fields comprising bacteria-infected and non-infected plants. This is particularly suitable to reduce or prevent secondary spread of the bacteria within the field.

Most plant pathogenic bacteria belong to the genera Erwinia, Arsenophonus, Phlomobacter, Serratia marcescens, Pectobacterium, Pantoea, Agrobacterium, Liberibacter, Pseudomonas, Ralstonia, Burkholderia, Acidovorax, Xanthomonas, Clavibacter, Streptomyces, Xylella, Spiroplasma, and Phytoplasma. Xyella, Liberibacter, Spiroplasma and Phytoplasma contain the most economically impacting diseases transmitted by hemipteran vectors within plants (c.f. Huang, Weijie PMC 2020 Dec 28). Preferred embodiments of the use or method according to the invention for reducing or preventing bacteria transmission from insect, especially Auchenorrhyncha vectors to sugar beet or potato crops comprising the application of dimpropyridaz are described herein.

Since it is known that bacteria can be acquired by infected plants in both vascular systems: phloem and xylem, the presumption is that majority of bacterial diseases, as vectored by insects, will be obligate intercellular persistent and semi-persistent, circulative, and non- circulative, and minority in non-persistent. It should also be noted that bacterial acquisition within plants can also occur via contaminated soil or seed, plant injury with exposure to infected debris or airborne spores. Several of the families that impact plant health also contain genera and or species that impact human (mammalian) health as well.

In one embodiment of the invention the pathogens are persistent bacteria. In another embodiment, the bacteria are non-persistent bacteria. In another embodiment, the bacteria are semi-persistent bacteria.

One embodiment of the invention relates to the use of dimpropyridaz for reducing or preventing the spread of non-persistent bacterium types. Another embodiment of the invention relates to the use of dimpropyridaz for reducing or preventing the primary spread of non-persistent bacterium types through rapid feeding cessation. Another embodiment of the invention relates to the use of dimpropyridaz for reducing or preventing the secondary spread of non-persistent bacterium types.

One embodiment of the invention relates to the use of dimpropyridaz for reducing or preventing the spread of persistent bacterium types. Another embodiment of the invention relates to the use of dimpropyridaz for reducing or preventing the primary spread of persistent bacterium types through rapid feeding cessation. Another embodiment of the invention relates to the use of dimpropyridaz for reducing or preventing the secondary spread of persistent bacterium types. Another embodiment of the invention relates to the use of dimpropyridaz for reducing or preventing the primary spread of non-persistent and semi-persistent bacteria types. Another embodiment of the invention relates to the use of dimpropyridaz for reducing or preventing the secondary spread of non-persistent and semi-persistent bacteria types.

For the reduction of secondary spread, it is required that the insecticide effectively kills all insect vectors, or rapidly ceases feeding of the vectors. However, fast-killing insecticides may have negative effects to non-target arthropods and beneficials. It has been found that dimpropyridaz effectively causes a rapid feeding cessation of insects by its unique mode of action. Accordingly, dimpropyridaz controls bacteria transmission by preventing the infection of the plant during the feeding process.

In one embodiment, the bacteria is selected from the families of Mycoplasmataceae, Acholeplasmataceae, Rhizobiaceae, and is preferably selected from the Spiroplasma, C. Phytoplasma, Liberibacter geneses respectively. In one embodiment, the bacteria is selected from the families of Enterobacteriales: Enterobacteriaceae. In another embodiment, the bacteria are selected from Spiroplasma spp.

The family Erwiniaceae contains genera Erwinia which includes more than 20 species, of which E. amylovora or fire blight appearing on pome and stone fruits may be the most common. Additionally, there is E. tracheiphila causing bacterial wilt in cucurbits and ornamentals such as orchid. As well as sub-genera Pantoea containing at least 9 species some of which are opportunistic and able to impact humans. Most common P. stewartia causing Stewart’s wilt in corn and other poaceae, such as sugarcane, bacterial leaf wilt, rice leaf blight, and jack-fruit bronzing disease.

The family Pectobacteriaceae contains genera Dickeya, Brenneria and Pectobacterium with 8 to 9 species per genera. Dickeya solani is a common example of bacterium that impacts potato and other solanaceous crops commonly known as blackleg or soft rot.

The family Rhizobiaceae over 20 genera including but not limited to Agrobacterium and Liberibacter. Agrobacteria are most noted for development of gall like growths and use in GMO transformations within a range of row crops such as soybean, cotton, maize, etc. Liberibacter is most noted for semi-persistent presence, hemolymph, and salivary glands, within psyllids, potato and Asian citrus psyllid, transmitting zebra chip disease in potatoes and solanaceous crops and Huanglongbing disease (HLB) or Citrus Greening in citrus.

The genera Pseudomonas, of family Pseudomonadaceae, express a range of plant diseases with common symptomology of rot, gall formation and necrosis and contain saprophytic plant growth promoting pseudomonas (PGPPs).

The family Burkholderiaceae contains two major plant infecting genera Ralstonia and Burkholderia. of infects a wide range of solanaceous crops such as potato, eggplant, tomato, wild woody nightshade, pepper, as well as soybean, ginger, and a range of ornamentals causing Ralstonia wilt.

The genera Burkholderia contains 20 or more species including Burkholderia glumae which causes grain and seedling rot in rice as well as wilt within solanaceous crops as well as sesame and others.

The family Xanthomonadaceae contains genera Xanthomonas of many species, nearly 30, that impact a wide range of more than 400 differing plant species. Responses in plants are ranging from citrus canker, by Xanthomonas citri and bacterial leaf spot and bacterial blight such as Xanthomonas oryzae of rice. This family also contains the genera Xylella which contains the species X. fastidiosa. X. fastidiosa is commonly vectored by leafhoppers such as sharpshooters and other hemipterans. Many diseases are associated across a wide range of crops including but not limited to, bacterial leaf scorch in oleander and coffee, alfalfa dwarf, Pierce’s disease in grapes, olive quick decline syndrome in olive trees and citrus variegated chlorosis in citrus.

The genera Clavibacter of the family Microbacteriaceae causes bacterial canker or ring rot via Clavibacter michiganensis impacting solanaceous crops including tomato.

The genera Streptomyces of the family Streptomycetaceae has at least 10 species that are plant pathogenic, but over 500 species within the family, causes lesions on tuber and root crops such as soleanceous, potato via S. scabies, but typically this genus is associated with soil borne pathogens and not vector borne.

The genera Xyella contains over 600 species that impact plants. Disease symptomology includes leaf cholorosis, withering, changes in internodal growth, changes in fruit size and abscission, sticky leaf appearance, etc. As an example, Xyella fastidiosa is an aerobic plant pathogen that harbors in xylem tissues and is transmitted by xylem feeding insects such as leafhoppers/sharpshooters and spittlebugs resulting in chlorosis, leaf scorch, etc. A specific result is Pierce’s disease (PD) in grapes.

The genera Spiroplasma, family Spiroplamataceae and class Mollicutes including several pathogens that cause diseases within plants but are also capable of infecting mammals and acting in a symbiotic way with same species, i.e., Drosophila sp. protection from parasitic nematodes or as a driver of speciation by impacting other arthropods including ladybug, bees, ants, beetles and butterflies via male-killing. Focus for crop diseases are Spiroplasma citri causing citrus stubborn disease and Spiroplasma kunkelii for corn stunt disease.

The genera Phytoplasma also of the class Mollicutes, containing genus Candidatus impact a tremendous range of crops including but not limited to tropical fruits (ex. coconut), stone fruits, sugarcane, and woody trees and are most commonly vectored by hemipteran pests. Phytoplasmas are obligate phloem tissue pathogens that require insect vectors for plant-to-plant transmission. Specific example of economic importance is Candidatus phytoplasma causing Maize bushy stunt vectored by corn leafhoppers, Dalbulus maidis. Another example is Candidatus Arsenophonus phytopathogenicus causing Syndrome Basses Richesses (SBR) vectored by Pentastiridius leporinus (Cixiidae). In one embodiment, the bacteria are Candidatus Arsenophonus phytopathogenicus. In another embodiment, the invention relates to the use or method for reducing or preventing bacteria transmission to plants, and protecting plants from bacterial diseases, which method or use comprises applying dimpropyridaz, wherein the bacteria are selected from Spiroplasma kunkelii and Candidatus phytoplasma.

Plant diseases caused by the aforementioned bacteria genera can be reduced or prevented, or the afore-mentioned plant can be protected by the inventive use of dimpropyridaz, or method of applying dimpropyridaz to the plants, to both the non-infected or infected plants.

For certain bacteria, certain insect vectors can be identified. For example:lf the insect vector is a leafhopper, such as Dalbulus maidis, bacteria such as Spiroplasma kunkelii (Mollicutes- bacteria), and Maize bushy stunt phytoplasma (MBSP) are transmitted. Citrus greening (HLB) is vectored by Asian citrus psyllid (Diaphornia citri).

Flavescence doree (FD-C & FD-D) are vectored by Scaphoideus titanus.

In a preferred embodiment of the invention, the plants are selected from the group consisting of Alfalfa, barley, beans, beets, brassicas, cabbage, carrots, cauliflower, celery, chervil, chickpea, clover, coriander, courgette, cucumber, cucurbits, eggplants, fava bean, fodder beets, gherkins, lentil, lettuce, lucerne, lupin, maize, marrows, melons, mustard, oats, oilseed rape, ornamentals, parsley, parsnip, peas, peppers, potatoes, pumpkins, quinoa, radish, rape, rice, safflower, soya, spinach, squashes, sugar beet, tobacco, tomato, triticale, turnip, watermelon, and wheat. In a particularly preferred embodiment of the invention, the plants are selected from the group consisting of tomato, eggplants, potatoes, tobacco, beans, peppers, Oilseed rape, physalis plants, brassicas, lettuce crops, mustard, chickpea, lupin, lentil, beans, peas, lucerne, clover, Barley, wheat, oats, maize, triticale, rice, sugar beet, and fodder beets. In another embodiment, the plants are sugar beet plants. In another embodiment, the plants are potatoes, sugar beet and fodder beet plants.

In one embodiment, the invention relates to the use or method for reducing or preventing bacteria transmission to plants, and protecting plants from bacterial diseases, which method or use comprises applying dimpropyridaz, wherein the plant is of Poaceae, preferably maize (syn. corn).

Individual embodiments of the invention are such methods or uses for reducing or preventing bacteria transmission from insect vectors to plants, wherein the insect vector, the bacterium and the plant is as defined in entries 1-1 to I-9 of Table A.1 which method or use comprises applying dimpropyridaz to the respective crop.

Table A.1

Individual embodiments of the invention are such methods or uses for reducing or preventing bacteria transmission from insect vectors to plants, wherein the bacterium and the plant is as defined in entries AB-1 to AB-4 of Table A.2 which method or use comprises applying dimpropyridaz to the plant. Individual embodiments of the invention are such methods or uses for protecting plants from bacterial diseases, wherein the bacterium and the plant is as defined in entries AB-1 to AB-4 of Table A.2 which method or use comprises applying dimpropyridaz to the plant.

Table A.2

These bacteria are preferably spread by insects as defined above, e.g., by one or more of leafhopper species like Dalbulus maidis and/or Diaphornia citri.

Individual embodiments of the invention are such methods or uses for protecting plants including but not limited to bacterial diseases, wherein the mainly affected plant/crop, the bacteria, and the transmitting insect, is as defined in entries C-1 to C-5 of Table C, which methods or uses comprise applying dimpropyridaz to fields comprising non-infected or infected plants. List is reduced to showcase bacteria of economic importance that likewise correlates with insect vector-based transmission. Table C

Particular embodiments of the invention are such methods or uses for protecting corn plants from transmission of the bacterial diseases Corn stunt spiroplasma (CSS) caused by Spiroplasma kunkelii, and Maize bushy stunt phytoplasma (MBSP) caused by Candidatus phytoplasma, by the transmitting insect Dalbulus maidis (corn leafhopper), which methods or uses comprise applying dimpropyridaz to fields comprising non-infected or infected plants.

Furthermore, it has been found that dimpropyridaz is especially suitable for the purpose of the invention, if applied in combination with a further pesticidally active compound. Such combinations and mixture ratios are known e.g., from WO2013/189801, WO2016/128261 , and WO2018/234478.

Accordingly, the invention therefore relates to the use or method for reducing or preventing bacteria transmission from Auchenorrhyncha vectors to plants, which method or use comprises applying dimpropyridaz which is applied in combination with at least one further pesticidally active compound. Another aspect of the invention relates to a method for protecting plants from bacterial diseases which method comprises applying dimpropyridaz which is applied in combination with at least one further pesticidally active compound.

Dimpropyridaz for use in this invention can be used in customary types of agrochemical compositions, e.g., solutions, emulsions, suspensions, dusts, powders, pastes, granules, pressings, capsules, and mixtures thereof. Examples for composition types are suspensions (e.g. SC, OD, FS), emulsifiable concentrates (e.g. EC), emulsions (e.g. EW, EO, ES, ME), capsules (e.g. CS, ZC), pastes, pastilles, wettable powders or dusts (e.g. WP, SP, WS, DP, DS), pressings (e.g. BR, TB, DT), granules (e.g. WG, SG, GR, FG, GG, MG), insecticidal articles (e.g. LN), as well as gel formulations for the treatment of plant propagation materials e.g. seeds (e.g. GF). These and further composition types are known from WO2012143317. The agrochemical compositions generally comprise between 0.01 and 95%, preferably between 0.1 and 90%, and most preferably between 0.5 and 75%, by weight of active substance. The active substance is employed in a purity of from 90% to 100%, preferably from 95% to 100%. The user applies the composition according to the invention usually from a pre-dosage device, a knapsack sprayer, a spray tank, a spray plane, or an irrigation system. Usually, the agrochemical composition is made up with water, buffer, and/or further auxiliaries to the desired application concentration and the ready-to-use spray liquor or the agrochemical composition according to the invention is thus obtained. Usually, 20 to 2000 liters of the ready-to-use spray liquor are applied per hectare of agricultural useful area.

The application can be carried out both before and after the infestation of the crops, plants, plant propagation materials by the insect vector. Preferably, the application is carried out before the crops, plants, plant propagation materials are infected with the bacteria by insect vector. Dimpropyridaz can be applied as such or in form of compositions comprising them, preferably SL and SC formulations.

In a preferred embodiment of the use or method of the invention, dimpropyridaz is applied to the foliage of the plants, preferably in an amount of from 20 g to 200 g per hectare, more preferably in an amount of from 30 g to 150 g per hectare, e.g., from 90 g to 120 g or from 120 g to 150 g or from 30 g to 120 g per hectare.

In another embodiment of the use or method of the invention, dimpropyridaz is applied to the seeds of the plant, preferably in an amount of from 1 g to 200 g per 100 kg seed, preferably from 5 g to 100 kg per 100 kg of seed, e.g., from 10 to 30 g or from 40 to 60 g or from 70 to 90 g per 100 kg of seed.

Examples

The invention is illustrated in further detail by the following biological examples.

Examples across both lab and field environments present a strong trend relating dimpropyridaz use, either in a preventative, prior to vector insect natural or artificial infestation, or curative, maximal plant, and insect contact, to a greater reduction in overall presence of related plant diseases by crop system compared to other insecticides. Based on feeding EPG, honeydew clock and related field trials it is concluded that dimpropyridaz drives a reduction in feeding both in duration probing and salvation or ingestion. Correlation of these laboratory results were mirrored in overall presence of disease as noted visually that reduction in disease presence was independent of noted pest populations. Dimpropyridaz was used as a 120g/l SL formulation in Experiments 1 to 5. The formulations were diluted with water to give the spray liquids for use in the experiments below.

Imidacloprid was used as a commercial formulation, dilution, and applied rate according to its label. All treatments were applied using a backpack pressurized

Example 1 : Disease transmission reduction and mortality on Dalbulus maidis control Insects that are vectors of two major pathogens leading to maize stunting in corn, Mollicutes bacteria, Spiroplasma kunkelli, and Maize bushy stunt phytoplasma can be a big problem for growers, since some time may pass before the insecticide kills the insect, during which the insect can transmit the disease to a healthy plant. The relation of bacteria vector of Dalbulus maidis (Corn leafhopper, DALBMA) is a persistent manner, which means, the insect can transmit or acquire the disease only if its feeds for a longer duration of time in the phloem vessel. In this case a good insecticide for disease vector, needs to kill the insect but moreover needs to quickly stop feeding activities to avoid disease transmission.

Corn plants of Zea mays (ZEAMX) were planted using normal spacing for variety AG 8480 PRO3 (row spacing 0.5m and plant density 4 plant/m). Plots size was 6x6m (36m²).

Treatments were applied via foliar application five days after emergence and was repeated every 5 days. Total number of applications within trial period was seven. Spray volume was 120L/ha and nozzles used to do the application was XR 110.02, spacing between nozzles 0.5m and pression 2.5 bar. Average application time for full study ranged from -30-50 minutes.

Dimpropyridaz was used as a 120g/L SL formulation compared to commercial standards tested: Thiamethoxam + Lambda cyhalothrin: Engeo® Pleno 141g/L+106g/L SC (Syngenta);

Imidacloprid + Bifenthrin: Galil® 300g/L SC (ADAMA) in the rates shown below.

Different assessments were conducted throughout the trial period:

NUMBER: count number of insects alive in 15 central plants on the plot.

INFECT: Evaluate 15 central plants on the plot and evaluate according to scale of stunting symptomology severity.

Scalel : plant without symptom

Scale 2: Plants with leaves less of 25% of symptoms (leave red or yellow)

Scale 3: plants with leaves 25-50% with symptoms

Scale 4: Plants with leaves 50-75% with symptoms Scale 5: Plants with leaves more than 75% with symptoms

Scale 6: plants died due to symptoms

YIELD: harvest (kg/ha)

Table 1-1: Results based on averages of replicates, subsamples per plot of: Efficacy (%) control of Dalbulus, Stunting symptomology severity (scale 1-6) and Harvest (kg/ha)

The results show the impact of dimpropyridaz treatment on bacterial disease transmission for Dalbulus maidis on corn crop. Percent efficacy of vector, population control, dalbulus, by dimpropyridaz at 108g ai/ha rate showed comparable efficacy as imidacloprid + bifenthrin at G05 and G10, 17.8, 16.7 and 14.6, respectively. Via 120g ai/ha rate dimpropyridaz showed higher efficacy than imidacloprid + bifenthrin and lower efficacy compared with thiamethoxam + lambda cyhalothrin E05 through G10, i.e., at G1041.5, 14.6 and 88.3, respectively. Key attributes noted by dimpropyridaz at both 108 and 120gai/ha rates compared with commercial standards are seen through the lower stunting symptomology severity response as well as higher total yield by weight kg/ha. Though thiamethoxam + lambda cyhalothrin resulted in higher percent efficacy control of dalbulus population throughout the study, it did not reduce symptomology severity or harvest kg/ha to the same level as dimpropyridaz. Dimpropyridaz at 108g ai/ha reduced severity of stunting symptoms by 2.5x and at 120gai/ha, 3x compared with the untreated control. Reduction in stunting symptomology directly correlated with total harvested kernels by weight within study wherein dimpropyridaz treatments were about 1 ,4x higher than the untreated control and thiamethoxam + lambda cyhalothrin treated plots and about 1.3x higher than the imidacloprid + bifenthrin treated plots. These results demonstrated the importance of rapid feeding cessation of dimpropyridaz in protecting crops and yields from plant disease infection.

Example 2: Bacteria transmission (EPG Studies)

The most powerful technique to study the feeding behaviour and plant penetration activities of sap-sucking insects is the electrical penetration graph technique (EPG) (Tjallingii, Entomologia Experimentalis et Applicata 24: 521-530 (1978); Entomologia Experimentalis et Applicata 38, 177-186 (1985)). EPG is an electrical system in which an insect with piercing mouthparts and a plant are made part of an electrical circuit as soon as the insect inserts its mouthparts (stylets) into the plant. As a result, voltage fluctuations are produced and can be recorded as waveforms, thus monitoring the insect's feeding activities and the stylet tip positions in the plant. These voltage fluctuations are due to resistance (R) or electromotive force (emf) changes occurring during stylet penetration. EPG recording has allowed the study of the stylet penetration activities of insect vectors in real time and facilitated correlation of the insect's probing activities with inoculation or acquisition of various plant pathogens (Prado & Tjalli ngii , Entomologia Experimentalis et Applicata 72: 157-165 (1994); Jiang et al., Annals of the Entomological Society of America 93, 573-579 (2000); Bonani et al., Entomologia Experimentalis et Applicata 134, 35-49 (2010)). It has also been widely used to understand how chemical compounds may affect the feeding behaviour of sap-sucking insects are exposed (e.g., Harrewijn & Kayser, Pesticide Science 49, 130-140 (1997); Jacobson & Kennedy, Pest Management Science 70(5):836-40 (2014)). EPGs have also been recently used as a new tool to monitor the early stages of aphid resistance to insecticides (Garzo et al., Pest Management Science 72(4), 707- 18 (2016)).

The EPG technique (Tjallingii 1978) was used to conduct the experiments. EPGs were used to show the impact on corn leafhopper (Dalbulus maidis, DALBMA) feeding behaviour on corn plants (Zea mays, ZEAMX) previously treated with the selected active ingredients. For these experiments an 8-channel DC-EPG (Giga-8 dd) (electrical penetration graph) divide was connected to an A/D converter card and a personal computer using Stylet⁺ d software for data acquisition and analysis. Waveform pathways that were monitored for output from corn leafhopper feeding include, C = Parenchyma pathway, G = Ingestion from Xylem, E1 = salivation into phloem and E2 = ingestion from phloem. Dalbulus maidis vector bacteria in a persistent manner, which means, the insect can transmit or acquire the disease only if its feeds for a longer duration of time in the phloem vessel. In this case a good insecticide for disease vector, needs to kill the insect but moreover needs to stop feeding activities to avoid disease transmission.

Treatments were applied via foliar application. 10 replicates per treatment, 1 insect per plant. Plants were sprayed at the recommended dose with an airbrush sprayer and after the plants dried, EPG plant setup was arranged. The corn leaf hoppers were immobilized under vacuum and cold plate, respectively and connected to a 17 pm, gold wire with the help of silver conductive paint.

Then, insects were connected to a copper electrode and to the DC-EPG device. A plant electrode was used to complete the circuit. EPG signals were acquired for each insect on a different plant and a minimum of 10 replicates per treatment was recorded, interpreted, and analysed. All behavioural variables were processed using the EPG-Excel data Worksheet developed internally.

DC-EPG (Giga-8 dd) output was conducted during a continuous 24-hour recording.

Dimpropyridaz was used as a 120g/L SL formulation compared to commercial standard Thiamethoxam + Lambda cyhalothrin: Engeo® Pleno 141g/L+106g/L SC (Syngenta). Rates of the test compounds:

EPG Results

Table 2-1: Total duration of each waveform (Total probe, C, G, E1, and E2) during 24 hours of analysis of the EPG recording

Results show the strong impact on the feeding behaviour of dimpropyridaz and other chemical compounds against corn leafhoppers. Phloem is the vessel where Dalbulus maidis can transmit stunting disease for corn. The relation of bacteria mollicute, phytoplasma to vector is in a persistent manner, which means the insect can transmit or acquire the disease only if feed for longer time in this vessel. Dimpropyridaz presented with the lowest amount of time (minutes) total probing across all tissues most notably within phloem via salivation and ingestion. When compared to control, verify clear changes in feeding behaviour throughout 24 hours were observed wherein dimpropyridaz reduced the total amount of time for phloem salivation and ingestion, 12x, 37x to 57x, 6.9x respectively. When dimpropyridaz was compared to Thiamethoxam + Lambda cyhalothrin, dimpropyridaz numerically reduced phloem salivation (E1) by about 2x as well as phloem ingestion (E2) by about 3x, confirming interference regarding corn leafhopper feeding behaviour.

Example 3: Speed of feeding cessation - Honeydew clock results on Aphis gossypii (APHIGO)

Feeding cessation is a critical aspect regarding reduction of disease transmission amongst plant hosts. With differing impacts to insects based on coordination, active probing, feeding and mortality it is key to understand and relate results from EPG studies with a tangible and direct output of feeding. Honeydew is the sugary excrement as produced by piercing and sucking insects such as aphids and whiteflies and can be collected with water sensitive paper to correlate active feeding over an isolated range of time -24-48 hours. Amount of honeydew production is a direct representation of amount of feeding per hour. Even if insects are persisting on a plant and have not fully succumb to treatment reduction or inhibition of feeding during this period is essential for reduction in transmission of disease.

Cotton plants at growth stage BBCH 12, approximate height 30-35cm, were pre-trimmed to remove all but one single leaf. This leaf was further trimmed to form a rectangular shaped section along its mid-vein to not exceed 6-8mm width, ~24mm length and was supported by metal twist ties at a horizontal plan for the duration of the experiment. Once trimmed and supported, plants were infested with cotton aphids, received from an in-house established colony, via a pre-infested dicotyledon leaf clipping and allowed to settle on plant material for -12-24 hours prior to treatment. Number of aphids per trimmed plant/leaf were evaluated prior to application, with number of aphids per plant relatively similar amongst all treatments. Application was conducted and plants were allowed to dry for approximately 30 minutes. Treated plants were positioned so that, once dried, the treated leaf would rest 2-3mm above a moisture sensitive paper strip affixed to a 24-hour rotational clock timer (Intermatic Time-All model no. TN111C or TN311C). Moisture sensitive paper was coaxially mounted to the outer rim of a 60mm petri dish lid with double sided tape which was then attached to the front of a 24- hour clock timer via Velcro strips. Replicates were held in tandem on a seven-outlet power strip which was clamped to a rectangular steel base for support. Setups were maintained in under laboratory environmental conditions.

Treatments were applied via foliar dip application wherein infested plants were dipped into solutions of predetermined rates (ppm ai or gai/ha) prepared by formulated compounds diluted in deionized water. Plant foliage was submerged for 3 full seconds ensuring full coverage of plant piece. Total replicates per treatment was 3, totalling 180-300 aphids per treatment.

Test compounds: Dimpropyridaz was used as a 120g/L SL formulation compared to commercial standards Pymetrozine 50% WG (Fulfill®, Syngenta), Spirotetramat 240g/L OD (Movento®, Bayer) tested as commercial products.

Results

Table 3-1: Mean total number of aphid honeydew droplets 24-48 hours

Table 3-2: Repeated measurement mean number of aphid honeydew droplets per hour over 48 hours

Model = Generalized liner mixed model with negative binomial distribution (log link) and autoregressive 1 covariance structure. P = 0.05.

Results show the advantageous effect of dimpropyridaz treatment on reduction and time of cessation of honeydew production by cotton aphid (Aphis gossypii) on cotton compared with relevant global commercial insecticides. Dimpropyridaz showed the lowest number of aphid droplets across 24 - 48 hours (67.3). When average number of droplets per hour was evaluated dimpropyridaz showed a significant reduction noting the lowest number of honeydew droplets throughout the duration of the test. Reduction in feeding as seen by number of honeydew droplets per hour or in total confirm that dimpropyridaz displays feeding activity in a manner that correlates to reduction in disease transmission.

Example 4: Control of Pentastiridius leporinus in sugar beet plants

Sugar beet plants (BBCH 14) in pots were obtained from the University of Giessen. Planthoppers were collected in the field in Rhineland-Palatinate, Germany. The plants were sprayed using an automated sprayer at the BASF Agricultural station in Limburgerhof (HSSC APR/DT, nozzle: Lu 120 02, pressure: 3 bar). Treatments were according to Table 4-1

Table 4-1

After drying, plants were placed inside acryl glass cylinders (diameter: 132 mm; height: 350 mm) and then placed on a petri dish (diameter: 145 mm). The Cylinders were covered with a plastic mesh. Each plant was infested with 10 insects (females and males mixed). The plants were incubated at 23°C, 50% RH, 18h day/ 6h night light cycle. Planthopper mortality was assessed on the first, the fourth and the seventh day after infection (DAI). Table 4-2 lists the mortality for all applications and time points of observation:

Table 4-2: Mortality of Pentastiridius leporinus Example 5: Disease transmission reduction and mortality of dimpropyridaz on Dalbulus maidis (maize leafhopper; DALBMA) control - Field study

The objective of this trial was to further understand the impact of dimpropyridaz treatment on disease transmission for Dalbulus maidis on corn crops. The experiments were conducted in the following sites

Corn plants were planting using normal spacing for variety AG 8480 PRO3 (row spacing 0,5m and plant density 4 plant/m). Plots size were 6x6m (36m²). Treatments were applied via foliar application five days after emergence and was repeated every 5 days. Total number of applications within trial period was seven. Spray volume was 120L/ha and nozzles used to do the application was XR 110.02, spacing between nozzles 0,5m and pression 2,5 BAR.

Assessments: Different assessments were conducted throughout the trial period:

NUMBER: count number of insects alive in 15 central plants on the plot.

INFECT: Evaluate 15 central plants on the plot and evaluate according to scale of symptoms disease (severity).

Scalel : plant without symptom

Scale 2: Plants with leaves less of 25% of symptoms (leave red or yellow)

Scale 3: plants with leaves 25-50% with symptoms

Scale 4: Plants with leaves 50-75% with symptoms Scale 5: Plants with leaves more than 75% with symptoms

Scale 6: plants died due to symptoms.

PLANT HEIGHT (cm): evaluate 15 central plant the plant height (cm)

YIELD: harvest (kg/ha)

Rates of the test compounds Results:

Table 4-1 - Data results of Efficacy (%), Infect Disease infection (scale 1-6), Plant Height (cm) and Yield (kg/ha) on field trial.

Efficacy (%) was calculated using Henderson and Tilton formula according to NUMBER evaluation.

Statistical analysis was used Friedman, Tukey and Scott Knott (5%).

Conclusions: According to efficacy data, Dimpropyridaz was not statistically different than other products tested. Dimpropyridaz was statistically different to other products tested (Thiamethoxam + Lambda cyhalothrin and Imidacloprid + Bifenthrin) on Infect, Plant Height and Harvest evaluations. According to data Dimpropyridaz did not cause a strong knock down effect (mortality), but by way of its different mode of action caused reduction in feeding activity correlated with reduced disease transmission (main cause of yield loss) and increased plant height and ultimately yield.

Claims

Claims

1. Use of 1-[(1RS)-1 ,2-dimethylpropyl]-N-ethyl-5-methyl-N-pyridazin-4-yl-1 H-pyrazole-4- carboxamide (common name dimpropyridaz) of formula I: or a stereoisomer, tautomer, salt, or N-oxide thereof for reducing or preventing bacteria transmission from insect vectors to plants.

2. Use according to claim 1, wherein the insect vector is selected from Fulgoromorpha and Cicadomorpha.

3. Use according to any one of claims 1 to 2, wherein the insect vector is Pentastiridius leporinus.

4. Use according to any of claims 1 or 2, wherein the insect vector is Dalbulus maidis.

5. Use according to any one of claims 1 to 4, wherein the transmitted bacteria are selected from Candidatus Arsenophorus phytopathogenicus, and Stolbur phytoplasma.

6. Use according to any one of claims 1 to 4, wherein the transmitted bacteria are Spiroplasma spp.

7. Use according to any one of claims 1 to 7, wherein dimpropyridaz is applied to fields of non-infected plants.

8. Use according to any one of claims 1 to 7, wherein dimpropyridaz is applied to fields comprising bacteria-infected and non-infected plants.

9. Use according to any one of the preceding claims, wherein dimpropyridaz is applied to the foliage of the plants.

10. Use according to any one of the preceding claims, wherein dimpropyridaz is applied in an amount of from 20 g to 200 g per hectare.

11. Use according to any of claims 1 to 3, 5, and 7 to 10, wherein the plants are selected from potatoes, sugar beet, and fodder beets.

12. Use according to any of claims claims 1 to 2, 4, and 6 to 10, wherein the plants are selected from corn.

13. Method for protecting sugar beet plants from Syndrome Basse Richesses disease, which method comprises applying dimpropyridaz to fields of non-infected plants as defined in any of claims 1 to 3, 5, and 7 to 10.

14. Method for reducing or preventing bacteria transmission from insect vectors to plants comprising the step of contacting the plants, parts thereof, their propagation material, the insects, their food supply, habitat or breeding ground with a pesticidally effective amount of dimpropyridaz or a stereoisomer, tautomer, salt or N-oxide thereof as defined in any of claims 1