AU2002100577B4 - Horticultural treatment process - Google Patents

Description

HORTICULTURAL TREATMENT PROCESS This innovation relates to the treatment of horticultural crops which are susceptible to fungal infection.

Background to the innovation Horticultural crops such as grapes, potatoes, chestnuts, tomatoes, citrus fruits,apples ,stone fruits, olives etc are susceptible to fungal infections. Some treatments to inhibit fungi leave residues that can be harmful to humans particularly if the fruits or crops are eaten fresh.

Grapes are an important commercial crop for both table and wine making.

Powdery mildew, downy mildew and botrytis including bunch rot [Botrytis cinerea] are fungal infections that can be harmful to both the grape and the wine. Bunch rot releases laccase an enzyme which in wine accelerates oxidation and the deterioration of the wine.

European patent application 242990 discloses examples of the treatment of cereal crops with peracetic or perpropionic acid to combat fungi and microbial infestations.

Currently in Australia there is no peracid product registered with the National Registration Authority for the treatment of fungal infestations in horticultural products. This may be because the formulations disclosed in the above patent were not seen as effective or were too costly to apply in the field.

It is an object of this innovation to provide an improved cost effective treatment for horticultural crops that leaves no harmful residues.

Brief description of the innovation To this end there is provided a method of treating horticultural crops susceptible to microbial and fungal infestation which comprises spraying on the crop an aqueous solution of at least 0.01 moles per litre of an alkyl per carboxylic acid having 2 to 6 carbon atoms and an effective amount of a nonionic surfactant selected from one or more of an alkoxy ether sulphate, branched or C12-C18 straight chain fatty acids, fatty alcohol ethoxy sulfates, amino alkyl betaines, alkanolamines, ethoxylated fatty amines, long chain aliphatic amine oxide and ethoxylated C9-C 11 alcohols.

The presence of the selected surfactant improves the cost and effectiveness of the treatment because the contact time of the active ingredient on the crop and its leaves is longer. It has also been observed that runoff is reduced with the consequence that less active ingredient is required per hectare of crop and this reduces the application cost to the grower.

This innovation is also partly predicated on the discovery that the per acid inhibits the action of laccase produced by bunch rot in grapes.

In another aspect this innovation provides a concentrated solution suitable for dilution prior to spraying on crops which includes a per carboxylic acid of 2to 6 carbon atoms, hydrogen peroxide and from 50 to 100% by weight of the per acid of a wetting agent selected from an alkoxy ether sulphate and/or a long chain aliphatic amine oxide.

The per acid is preferably per acetic acid prepared by heating an excess of hydrogen peroxide with acetic acid for a time sufficient to convert the acetic acid to per acetic acid.

The preferred nonionic surfactants are o Alkyl ether sulphates Oxamin LO amine oxide Ethoxylated C9-C11 alcohol Teric N 1 Nonyl phenol reacted with 11 moles of ethylene oxide CAS NO 9016-45-9 Teric 168 Teric N8 Nonyl phenol reacted with 8 moles ethylene oxide.

CAS NO 9016-45-9 Teric G9A6 Synthetic ethoxylated C9-Cl alchohol CAS NO 68439-46-3 Teric PE 62 Proplene glycol ethoxylate CAS NO 9003-11-6 e Octanoic acid The most preferred surfactant is a mixture of sodium lauryl ether sulphate and an amine oxide sold under the brand name Oxamin LO.

Because the active agent breaks down to acetic acid it is ideal for use on crops that are minimally processed for fresh consumption.

Detailed description of the innovation The following formulations were used for experimental treatments: Active Content Type Hydrogen peroxide 350 g/L Soluble Peroxyacetic acid 140 glL concentrate Amine Oxide Sod.Alkyl Ethoxysulphate Example A field trial was conducted to evaluate the efficacy and safety of Perfoam Fungicide as a curative, pre-harvest spray for the control of Bunch Rot disease of grapevines, caused by Botrytis cinerea. This trial was located in, Victoria, Australia on Chardonnay grapevines on a commercial vineyard, with evidence of Bunch Rot at the time of application.

Two applications were made of the following treatments: Formulation Rate of Water Vol L/ha Rate of Product/ha Formulation 1 1% (1 L/100 L) 1000 Lha 10 L/ha 2. 2% (2 L/100 L) 1000 L/ha 20 Lha 3. Untreated control___ The standard schedule of sprays for the control of Bunch Rot was applied by the grower as part of normal practice prior to the test application. The first application was made six days before harvest and the second application was made three days before harvest. The experimental design was a large scale, un-replicated block, with four internal replicates for assessment. All treatments were applied using the grower's own field scale vineyard sprayer. The vines were sprayed overall with an emphasis on covering the bunch zone. A water volume of 1000 litres per hectare was used. Bunch Rot infection was assessed at harvest by examining 4 x 50 bunches per plot for the presence and severity of the disease.

Prior to the application of the formulation there was a substantial level of infection.

An assessment of the Bunch Rot infection was made three days after the second application, immediately before the commercial harvest.

Bunch Rot infection severity was assessed prior to harvest by examining 4 x consecutive bunches along a row of vines randomly selected within the plot for the presence and degree of the disease. The two middle rows were selected, leaving buffer rows between treatments. Each bunch was rated for the severity of infection depending upon the percentage of berries infected within the bunch. The following rating scale was used: 0 No berries infected 1 1-2% of berries infected 2 3-10% of berries infected 3 11-20% of berries infected 4 21-50% of berries infected >50% of berries infected From this data the percentage of infected bunches per plot and the mean infection severity rating per 50 bunches was calculated.

The trial was assessed three days after the second treatment Table 1 Grape Disease Trial Mean Bunch Rot cinerea] Infection at Harvest Treatment Rate Mean Bunch Mean LU/100 Rot Infection Bunches L Rating* Infected 1 1.0 0.57 a 44 a 2 2.0 0.50 a 37 a 3 Untreated control 0.99 b 65 b LSD 95% 0.22 13 Assessment of the grapes in the plot with the formulation applied at the 1% rate showed a significantly lower mean Bunch Rot infection severity (0.57 versus 0.99 for untreated control, p 0.05). The percent of bunches infected was also reduced significantly compared to the untreated control (44% compared to Assessment of the grapes in the plot with the formulation applied at the 2% rate also showed significantly lower mean Bunch Rot infection severity (0.50 versus 0.99 for untreated control, p 0.05). The percent of bunches infected was also reduced significantly compared to the untreated control (37% compared to There was no significant difference in the infection severity or percent bunches infected between the 1% and 2% rate of the formulation.

Laccase is an oxidising enzyme produced by grapes in response to being infected by the target disease Bunch Rot (Botrytis cinerea). The principal detrimental action of laccase is to accelerate oxidation in wine, which leads to problems in making quality wine.

A laboratory test can quantify the level of laccase enzyme activity in must and wine. For this test 50 bunches were selected randomly from each treatment and hand pressed. After minimal filtration a small sub-sample of must was stored frozen until dispatch to the analytical laboratory.

The analysis of the must from the three treatments showed no laccase activity.

Table 2 Grape Disease Trial Laccase Activity at Harvest, Treatment Rate LaccaseActivity 1/100 L 1 PERFOAM 1.0 <0.1

FUNGICIDE

2 PERFOAM 2.0 <0.1

FUNGICIDE

3 Untreated control <0.1 Leaves, shoots and fruit were examined for any sign of direct phytotoxicity from the fungicide treatments during the course of the trial.

No grapevine or bunch phytotoxicity was evident as a result of the application of the formulation.

Claims (3)

1. A method of treating horticultural crops susceptible to microbial and fungal infestation which comprises spraying on the crop an aqueous solution of at least 0.01 moles per litre of an alkyl per carboxylic acid having 2 to 6 carbon atoms and an effective amount of a nonionic surfactant selected from one or more of an alkoxy ether sulphate, branched or C 12 -C 1 8 straight chain fatty acids, fatty alcohol ethoxy sulfates, amino alkyl betaines, alkanolamines, ethoxylated fatty amines, long chain aliphatic amine oxide and ethoxylated C 9 -C11 alcohols.

2. A concentrated horticultural solution suitable for dilution prior to spraying on crops which includes a per carboxylic acid of 2 to 6 carbon atoms, hydrogen peroxide and from 50 to 100% by weight of the per acid of a nonionic surfactant selected from one or more of an alkoxy ether sulphate, branched or C 12 -C 18 straight chain fatty acids, fatty alcohol ethoxy sulfates, amino alkyl betaines, alkanolamines, ethoxylated fatty amines, long chain aliphatic amine oxide and ethoxylated Cg-C11 alcohols.

3. A concentrated horticultural solution as claimed in claim 2 which includes per acetic acid, an alkyl ether sulfate and a long chain amine oxide.