WO2000078144A1

WO2000078144A1 - Method of increasing the resistance of cultivated plants to phytopathogen fungi

Info

Publication number: WO2000078144A1
Application number: PCT/EP2000/005277
Authority: WO
Inventors: Wilhelm Rademacher; John-Bryan Speakman; Eberhard Ammermann; Gerd Stammler; Piet Creemers
Original assignee: Basf Aktiengesellschaft
Priority date: 1999-06-17
Filing date: 2000-06-07
Publication date: 2000-12-28
Also published as: AU5971200A; AR024574A1

Abstract

The invention relates to a method of increasing the resistance of cultivated plants to phytopathogen fungi. The inventive method is characterized in that the cultivated plants are treated with the growth-regulating acylcyclohexadiones according to formula (I).

Description

Procedure for increasing the resistance of crop plants to phytopathogenic fungi

description

The present invention relates to a process for increasing the resistance of crop plants to phytopathogenic fungi, characterized in that the crop plants are treated with growth-regulating acylcyclohexadions according to formula I,

where R is in particular hydrogen, a C ₁ -C ₆ -alkyl, Ci-Cβ-haloalkyl, C -C -oalkylthioalkyl or phenyl group (substituted or unsubstituted) and R 'for hydrogen, a Cl-C6-alkyl-, C3 -C6-cycloalkyl- ,. Benzyl (substituted or unsubstituted), phenylethyl, phenoxyethyl, 2-thienylmethyl, alkoxymethyl or alkylthiomethyl group and suitable salts of these compounds.

Preferred is a process in which prohexadione or its salts which can be used in agriculture, in particular the calcium salt (II),

or a method using Trinexapac-ethyl (III).

The crops are fruit trees from the rosacea family such as apple and pear, plum, plum, peach, nectarine and cherry, and grapevines.

The process increases the resistance to Venturia inaequalis in apples and pears to Botrytis cinerea in grapevines and to phytopathogenic fungi in cereals and peanuts.

The productivity of crops can be reduced in many ways by stress factors. These include: viral diseases, bacterial and fungal pathogens, damaging insects, nematodes, snails, bite, heat, coolness, cold, lack of water, too high water content in the soil, soil salinity, too high radiation intensity, too high ozone content, competition for light, water and nutrients due to accompanying flora, improper or not optimally applicable herbicide applications (especially in fruit crops), treatments with herbicides, insecticides, fungicides, bioregulators or leaf fertilizers with insufficient selectivity, leaf applications of pesticides or fertilizers during intensive sun exposure.

A number of these problems caused by stressors can be minimized through the use of pesticides, through the use of resistant plant material or through suitable cultivation techniques. However, the scope of these options is limited. Furthermore, e.g. phytopathogenic fungi often adapt to fungicides so that their effectiveness wears off. A similar adaptation also exists for initially "pathogen-resistant" breeds.

A novel method for improving plant productivity is to trigger the natural defense reactions of a plant by means of suitable exogenous signals before the onset of fungal attack, in order to minimize the effects of the stress. For example, the following agents: "Bion" (active ingredient: acibenzolar-S-methyl = benzothiadiazole) for inducing resistance to powdery mildew in cereals and "Oryzemate" (active ingredient: probenazole) for inducing resistance to Pyricularia oryzae in rice, annu. Rev. Phytopath. 35: 349-72 (1997).

There is also a need for resistance-inducing agents for permanent crops such as fruit and wine, especially since the introduction of resistant varieties is very time-consuming and time-consuming.

Various methods for inducing resistance to biotic and abiotic stressors in fruit trees are described in the literature. However, none of these methods shows one Adequate reliability or the associated processes are too complicated or too expensive for practical use.

The object of the present invention was to provide a simple and cost-effective method for increasing the resistance to attack by phytopathogenic fungi in crop plants.

The acylcyclohexadiones of the formula I have now surprisingly been found as inducers for resistance to phytopathogenic fungi. Structures of such compounds are described in U.S. Patents 4,560,403 and 4,693,745.

It is known that these substances have an action against the bacterial pathogen of the fire blight, Jones, A.L., New York Fruit Quarterly 7 (1), 19-21 (1999). Fire blight is triggered by the Erwinia amylovora bacterium and causes damage especially to pears, apples and quince. However, a direct or indirect effect on harmful fungi through such compounds has not been described. Treatment with Trinexapac-ethyl does not reduce the infestation of meadow panicle grass (Poa pra tensis) with Leptosphaeria korrae or Drechslera poae or the infestation of fescue (Festuca arundinacea) with Rhizoctonia solani (Sanders and Soika, 1992, Fungicide and Nematocide Tests 47: 301, 47: 300 and 47: 309). In the latter two publications, it is even reported that trinexapac-ethyl, when applied simultaneously with the fungicide "Banner" (active ingredient: propiconazole), reduces the fungicidal action of the fungicide.

In some publications it is mentioned that prohexadione-Ca can reduce the infestation of fruit trees with fungal diseases. However, these are theoretical considerations that are based on an improved microclimate in the tree top (triggered by the growth regulatory effects on the morphology of the tree top). Evidence of an actual reduction in infestation with fungal pathogens is not provided. [Evans, RR, Evans, JR and Rademacher, W. (1997): Prohexadione calcium for suppression of vegetative growth in eastern apples, Acta Horticulturae 451, 663-666; Winkler, VW (1997): Reduced risk concept for prohexadione-calcium, a vegetative growth control plant growth regulator in apples, Acta Horticulturae 451, 667-671; Deckers, T. and Daemen, E. (1998): Growth regulation in IFP production systems, lecture at the 4 ^th International Conference on Integrated Fruit Production, Leuven, Belgium, July 1998] In some places it is mentioned that acylcyclohexadiones such as Prohexadione-Ca or Trinexapac-ethyl protect crops against biotic and abiotic stressors (EP 0 126 713).

Prohexadione-Ca, trinexapac-ethyl and other structurally similar acylcyclohexadiones are known as growth retardants, a certain group of bioregulators. The compounds mentioned prevent the biosynthesis of gibberellins. Certain gibberellins cause, among other things, a stretching of the plant cells and thus have a considerable influence on the plant length growth. A treatment with Prohexadione-Ca or Trinexapac-ethyl accordingly leads to more compact plants, which can be of practical importance (e.g. reduction of the sedimentation of cereals, extension of the mowing interval for lawn grasses).

Other types of growth retardants have been variously tested for their ability to induce resistance to biotic or abiotic stress in crop plants. It is known that triazolyls, such as paclobutrazole and unicoazole, have a certain fungicidal action owing to their structural proximity to certain fungicides [cf. Rademacher, 1991, pp. 169-200, in: Plant Biochemical Regulators, H.W. Gausman (ed.), Marcel Dekker, Inc., New York]. Accordingly, there is no induced resistance to fungal attack. It is also not evident from the literature that a more compact growth caused by growth retardants generally leads to resistance to attack by fungal pathogens.

By treating the plants with acylcyclohexadions, prohexadione-Ca or trinexapac-ethyl, the flavonoids eriodictyol, proanthocyanidins which are substituted on the C atom 3 with hydrogen, e.g. Luteoforol, luteoliflavan, apigeniflavan and tricetiflavan, as well as homogeneous and heterogeneous oligomers and

Polymers are increasingly formed from the above-mentioned and structurally related substances.

Increased concentrations of the phenols hydroxycinnamic acid (p-coumaric acid, ferulic acid, sinapic acid), salicylic acid or umbelliferone, including the homogeneous and heterogeneous oligomers and polymers formed from them, can be applied to plants after application of the compounds acylcyclohexadione, prohexadione-Ca or trinexapacethyl be determined. Treatment with compounds from the group of acylcyclohexadions of the formula I, prohexadione-Ca or trinexapac-ethyl leads to an increase in the resistance to phytopathogenic fungi in fruit trees from the rosaceae family such as apple and pear, plum, plum, peach, nectarine and cherry as well in grapevine, against Venturia inaequalis in apple and pear and against phytopathogenic fungi in cereals and peanuts.

In general, the resistance to the following phytopathogenic fungi is increased by the treatment of the crop plants with compounds from the group of the acylcyclohexadione, prohexadione-Ca or trinexapac-ethyl.

The method according to the invention is particularly suitable for increasing the resistance to attack by the following phytopathogenic fungi:

Erysiphe graminis (powdery mildew) on cereals

Erysiphe cichoracearum and Sphaerotheca fuliginea grown on pumpkin

Podosphaera leucotricha on apples,

Uncinula necator on vines,

Puccinia species on cereals,

Rhizoctonia species on cotton, rice and lawn, Ustilago species on cereals and sugar cane,

Venturia species (scab) on apples and pears

Helminthosporium species on cereals,

Septoria species on wheat

Botrytis cinerea (gray mold) on strawberries, vegetables, ornamental plants and vines,

Cercospora arachidicola on peanuts,

Pseudocercosporella herpotrichoides on wheat and barley,

Pyricularia oryzae on rice,

Phytophthora infestans on potatoes and tomatoes, Plasmopara viticola on vines,

Pseudoperonospora species in hops and cucumbers,

Alternaria species on vegetables and fruits,

Mycosphaerella species in bananas and peanuts as well

Fusarium and Verticillium species in cereals, vegetables and ornamental plants.

The amount of effort in the treatment of crops with compounds from the group of acylcyclohexadione, prohexadione-Ca or trinexapac-ethyl to increase the resistance to attack by phytopathogenic fungi is between 1 and 2,000 g / ha, preferably between 5 and 800 g / ha of active substance.

The following examples demonstrate the action according to the invention of acylcyclohexadions such as prohexadione-Ca and trinexapac-ethyl on the induction of resistance to fungal attack in crop plants.

example 1

Ineffectiveness of prohexadione-Ca as a fungicide

The fungal organisms Al ternaria al ternata, Aspergill us niger and Penicillium funiculosum were cultivated on nutrient media to which 50, 100, 250, 500 or 1000 ppm of prohexadione-Ca had been added. - Compared to the control without the addition of an active ingredient, no inhibitory effect on fungal growth was found. These results show that prohexadione-Ca does not have an immediate fungicidal effect. Similar findings can also be assumed from structurally related compounds.

Example 2

Induction of resistance to scab infestation (Venturia inaegualis) in apple (greenhouse trial)

Apple seedlings were grown to the 5-leaf stage under greenhouse conditions, in order then to be treated to runoff point with aqueous preparations of prohexadione-Ca containing 50, 100 or 200 ppm of active substance. After 1, 7, 14 and 21 days (TNB), the youngest fully developed leaves were inoculated with a spore suspension (5.2 to 5.8 x 10 ⁵ conidia per milliliter) from Venturia inaegualis to dripping wet. The infestation was evaluated 13 or 20 days later (TNI). - The results obtained are shown in Table 1.

Table 1

nb = not determined

Example 3

Apple seedlings were grown to the 5-leaf stage under greenhouse conditions, in order then to be treated to runoff point with an aqueous preparation of prohexadione-Ca containing 100 ppm of active substance. After 7, 10, 14, 21 and 7 + 21 (double treatment) days (TNB) the youngest fully developed leaves were inoculated with a conidia suspension (approx. 1.5 x 10 ⁵ spores per milliliter) from Venturia inaegualis. "Discus", BASF AG, Ludwigshafen (active ingredient: Kresoxim-methyl) was used with 100 ppm of active substance as a comparative agent one day before the inoculation. The evaluation of the fungal attack took place 17 and 24 days later (TNI). - The results obtained are shown in Table 2.

Table 2

nb = not determined - = not determined (infection levels similar to 1 TNB are expected)

- = not determined (an increase in infestation is to be expected as the time between fungicide treatment and inoculation increases)

Example 4

Induction of resistance to scab infestation (Venturia inaegualis) in apple

(Vegetation hall test)

Apple seedlings were grown to the 5-leaf stage under greenhouse conditions and then cultivated further for one week under open-field conditions (vegetation hall). The plants were then treated with aqueous preparations of prohexadione-Ca containing 50, 100 or 200 ppm of active substance until dripping wet. After 6, 13, 19, 26 and 34 days (TNB), the youngest fully developed leaves were inoculated with a conical suspension (5.2 to 5.8 x 10 ⁵ spores per milliliter) from Venturia inaegualis to dripping wet. The infestation was evaluated 13 or 20 days later (TNI). - The results obtained are shown in Table 3.

Table 3

Example 5

Reduction of scab infestation in apple by pretreatment with Prohexadione-Ca

(Field trial)

In 1998, under the growing conditions of the Gorsem Royal Research Institute (Sint-Truiden, Belgium), scab attacks were carried out on the "Golden Delicious" and "Jonagold" varieties. Prohexadione-Ca was integrated into a treatment program for scab control and applied at the development stages 55-56, 61 and 71, each with 100 g / ha of active substance. - The untreated plants had a significant infestation with scab on leaves and fruit. In contrast, no or only a greatly reduced infection was found in the plants which had been treated with prohexadione-Ca, among other things. On the basis of the active ingredients used here overall and the application dates chosen, it can be assumed that the effect achieved is to a large extent attributable to the use of prohexadione-Ca. The scab effect was almost comparable to the effect of the standard fungicide "Scala" (active ingredient: pyrimethanil), which was applied at the development stages 54, 55, 56, 61, 65, 71, 72 and 73 with 450 g / ha of active substance each was. Tables 2 to 4 show that the infestation of apple plants with apple scab can be significantly reduced by pretreatment with prohexadione-Ca. This is particularly evident in the plants cultivated under field-like conditions (Table 2 and Example 4). It also shows that a period of several days is required after the application of prohexadione-Ca before the infection is reduced. This indicates that the active substance itself has no fungicidal activity (as can also be seen from Example 1), but rather that it triggers a defense reaction in the plant, which leads to increased resistance to scab infestation.

Example 6

Induction of resistance to Botrytis cinerea in red table grapes

(Variety: "Catawba")

Table grapes of the "Catawba" variety were cultivated in the 1996/97 season under the growing conditions of the BASF test station Nelspruit in the Republic of South Africa. At the developmental stage 75 (berries about the size of a pea) and 14 days later, the fruit stalks were sprayed twice with 500 or 1000 ppm of active substance from prohexadione-Ca to dripping wet. After harvesting the ripe grapes, individual berries were injured by a pin prick and then placed briefly in a spore suspension of Botrytis cinerea. The berries were then incubated at 23 ° C. for about 7 days. The degree of infestation of the berries with Botrytis cinerea was then determined: While the untreated berries were very heavily infested, pretreatment with twice 500 ppm of prohexadione-Ca led to a significantly reduced infection. A double application of 1000 ppm of Prohexadione-Ca almost completely prevented infection.

From example 6 it can be seen that prohexadione-Ca can also cause a reduced susceptibility to a fungal pathogen in the wine plant species not related to apple.

Example 7

Induction of resistance to Botrytis cinerea in red grapes

(Variety: "Dornfelder") "Dornfelder" grapes were cultivated in the 1998 season under the growing conditions of the Palatinate. The grapes were treated analogously to Example 6. The results after infection with spores of Botrytis cinerea were practically congruent with those from Example 6.

Example 7 also shows that prohexadione-Ca can also cause a reduced susceptibility to a fungal pathogen in the wine plant species, which is not related to apple.

Claims

claims

1. A process for increasing the resistance of crop plants to phytopathogenic fungi, characterized in that the crop plants are treated with growth-regulating acylcyclohexadions according to formula I,

where R is in particular hydrogen, a C ₁ -C ₆ alkyl,

-C-C ₆ -Haloalkyl-, C ₂ -Cι ₀ -Alkylthioalkyl- or phenyl group (substituted or unsubstituted) and R 'for hydrogen, a Cl-C6-alkyl, C3-C6-cycloalkyl, benzyl (substituted or unsubstituted ), Phenylethyl, phenoxyethyl, 2-thienylmethyl, alkoxymethyl or alkylthiomethyl group and suitable salts of these compounds.

2nd Process according to Claim 1, in which prohexadione or its salts which can be used in agriculture, in particular the calcium salt (II), are used in amounts of between 1 and 2,000 g / ha, preferably between 5 and 800 g / ha, of active substance (based on prohexadione) become.

3. The method according to claim 1, in which Trinexapac-ethyl (III) is applied in amounts of between 1 and 2,000 g / ha, preferably between 5 and 800 g / ha, of active substance.

4. The method according to claim 1-3, characterized in that the crops are fruit trees from the rosaceae family such as apple and pear, plum, plum, peach, nectarine and cherry and grapevines.

5. The method according to claim 1-3, characterized in that the resistance to Venturia inaegualis in apple and pear is increased.

6. The method according to claim 1-3, characterized in that the resistance to Botrytis cinerea is increased in grapevines.

7. The method according to claim 1-3, characterized in that the resistance to phytopathogenic fungi in cereals and peanuts is increased.