5.4 Other Materials (Defense Inducers, Plant Growth Regulators, and Biopesticides)

Acibenzolar-S-methyl (Actigard) is a systemic acquired resistance inducer. The material acts by inducing natural plant defenses to protect against infection bacteria and fungi. Trees with young tissue will respond better to the product than older trees. It’s an attractive option for apple growers during establishment years when one doesn’t wish to use prohexadione calcium to manage fire blight (shoot blight) as it restricts host growth. Actigard may be used in a drench in 8-16 fl oz water per tree. Drench applications may be fairly effective in 1-2 year old trees timed at green tip, but labor availability may make the practice less feasible in large operations. Actigard, may also be used in a foliar application, beginning at 20% bloom to ensure that host response is high when shoot blight infections occur later in the season. A minimum of 5 days is needed for the best induced resistance response.

Aureobasidium pullulans strains DSM 14940 & 14941 (Blossom Protect) is a combination of two yeast formulated with a buffer labeled on apples for use against fire blight. The material acts by colonizing the flowers and competitively excluding the fire blight bacterium from multiplying on the stigmatic surface on flowers; thereby preventing infection. It is highly effective and can be equally effective as streptomycin. It it is also OMRI listed. Repeat application can be made throughout bloom and a petal fall to prevent the development of fire blight. Appplications in rainy weather after petal fall are not advised as sensitive variaties may russet. It also not compatible with applications of captan.

Bacillus amyloliquefaciens strains D747, FZB24, MBI600, F727 (DoubleNickel 55/LC, Taegro, Serifel, Stargus) is a biofungicide labeled for control of fire blight, apple scab, powdery mildew, and summer diseases like fly speck and sooty blotch. Double Nickel 55 is a 25% water-dispersible granule (WDG) formulation, while Double Nickel LC is a 99% aqueous suspension of the bacterium Bacillus amyloliquefaciens, a common soil resident. The bacterium acts by releasing lipipeptides during growth that destroy the cell walls of plant pathogenic fungi and bacteria. DoubleNickel may be less effective than conventional fungicide for controlling fungal diseases under the favorable climatic conditions that exist in New York. However, tests at Cornell AgriTech have indicated that it provides good control of fly speck and sooty blotch when used in combination with low MCE organic copper (e.g. Cueva). When used alone, DoubleNickel provides only some control of fire blight. In alternation with streptomycin, it sometimes provides control approaching that of a full streptomycin program. DoubleNickel should be applied as a preventive and can be applied up to and including the day of harvest.

Bacillus mycoides isolate J (Lifegard) is a natural systemic acquired resistance inducer labeled for apples against fire blight. The material acts by inducing natural plant defenses to protect against invasion and migration of the fire blight bacterium. Younger trees and young shoot tissue will respond better to the product than older trees with heart wood tissues. It’s an attractive option for apple growers during establishment years when one doesn’t wish to use prohexadione calcium to manage fire blight (shoot blight), which slows host growth. Lifegard is made as a foliar application, beginning at 20% bloom to ensure that host response is high when shoot blight infections occur later in the season. A minimum of 5 days is needed for the best induced resistance response. Repeat application can be made throughout bloom and a petal fall to restrict the development of fire blight.

Bacillus subtilis strains QST 713, AFS032321, QST 713 (Serenade ASO, Theia, CEASE) is a biofungicide labeled for control of fire blight, apple scab, powdery mildew, and some other fungal diseases. The bacterium acts by releasing cell contents during growth in order to eliminate or reduce competitors in its immediate environment. Serenade may be less effective than conventional fungicide for controlling fungal diseases under the favorable climatic conditions that exist in New York. When used alone, Serenade provides only some control of fire blight. In alternation with streptomycin, it sometimes provides control approaching that of a full streptomycin program. Serenade should be applied as a preventive and can be applied up to and including the day of harvest.

Bacteriophage (AgriPhage) is a virus labeled to control bacteria such as Erwinia amylovora. The material acts on contact by injecting its DNA into the bacteria cells. Inside the cell, the phage begin replicating creating more and resulting in the destruction of the bacteria cell. It is a selective material and will not harm beneficial bacterium. Agriphage can be mixed and rotated as part of IPM programs. Most effective when used preventatively and curative at the first signs of disease. It has 0-day PHI.

Hydrogen Dioxide (Oxidate 1.0/2.0/2.5) with peroxyacetic acid is a broad spectrum bactericide, fungicide, and algaecide. This product works by destroying cells and preventing reproduction. Labeled for leaf spot, fire blight, sooty blotch, mildews and numerous rots. For fire blight control, apply during bloom and petal falls stages. Do not mix with any oils. It has a 0-day PHI.

Pseudomonas chlororaphis strain AFS009 (Howler EVO) is a biofungicide labeled for control of fire blight, apple scab, powdery mildew, and summer diseases like fly speck and sooty blotch. Howler EVO may be less effective than conventional fungicide for controlling fungal diseases under the favorable climatic conditions that exist in New York. However, tests at Cornell AgriTech have indicated that it provides good control of fly speck and sooty blotch when used in combination with low MCE organic copper (e.g. Cueva). When used alone, Howler EVO provides only some control of fire blight. To enhance performance, consider adding a surfactant that is known to be safe to the target crop to the spray tank. Howler EVO should be applied as a preventive and can be applied up to and including the day of harvest.

Phosphorous Acid (Fosphite, Fungi-Phite) and Phosphites (Phostrol, ProPhyt) can be viewed as generic forms of Aliette and are labeled on tree fruits primarily for control of root and crown rot diseases caused by Phytophthora species. However, some products are also labeled for suppression of fire blight, blister spot, and summer diseases, like sooty blotch and fly speck. Experience in NY suggests they do not provide reliable suppression of fire blight when applied during bloom, but they can be very useful as part of a program for controlling blister spot. Research trials in Geneva and the Hudson Valley have demonstrated that the combination of captan 80 and phosphorus acid or phosphite fungicides (e.g. Helena ProPhyt) can provide a commercially acceptable level of control of fly speck and sooty blotch. Trials conducted outside of NY suggest that these products can also provide moderate to good control of these diseases alone or in rotation with other products. As with Aliette, using these products with or soon after copper fungicides can cause copper phytotoxicity.

Polyoxin D Zinc Salt (OSO 5%SC) is a biopesticide labeled for summer diseases in NY including fly speck and sooty blotch, bitter rot, and white rot. It is also labeled for apple scab and powdery mildew. It is labeled for several fungal diseases of peach in NY, including brown rot and scab. No more than 4.3 oz a.i./acre (equivalent to 6 applications at the maximum rate) may be applied per season. Polyoxin D zinc salt inhibits the production of chitin, which is an important component of fungal cell walls. It provides protectant activity, but no post-infection activity. It has a 0-day PHI.

Potassium Silicate (Sil-Matrix) is abroad spectrum preventative fungicide that acts as a physical barrier preventing pathogens from penetrating the leaf or fruit surface. Combatible with most agricultural pesticides. Labeled for control of powdery mildew, botrytis. Apply at a colume concentration of 0.25-1% spray solution and repeat applications no sooner than 7 days.

Potassium bicarbonate (Kaligreen, MilStop) is a broad-spectrum foliar fungicide. It acts by destroying fungal cells and altering pH levels on application site which prevents future fungal growth. Most effective when used as a preventative or at the first signs of disease. Milstop, when used in conjunction with CEASE, can prevent powdery mildew, botrytis, and bacterial leaf spot. It has a 0-day PHI.

Prohexadione calcium Apogee & Kudos are plant growth regulators that reduces shoot growth. It acts by inhibiting the biosynthesis of gibberellin, the plant hormone that regulates cell elongation. Prohexadione calcium does not have direct antibiotic activity against the fire blight bacteria, rather it prevents invasion from the site of initial infection. This growth regulator will not protect against initial infection of flowers, but it may slow the invasion of bacterial within infected floral tissues and prevent spread to subsequent tissues. For this use, early applications of prohexadione calcium may be applied at “Pink” as described in the 2EE labeling. Pink application may also reduce bitter pit in ‘Honeycrisp’. Prohexadione calcium will reduce the severity of shoot blight if applied 10-14 days in advance of infections. For maximum reduction in fire blight susceptibility and for shoot blight management, Apogee should be applied early in the growing season (when shoots are 1 to 3 inches long) and reapplied 14-21 days later to prevent vigorous shoot growth. Prohexadione calcium may be helpful in rescuing orchards of 5 or more years developing considerable shoot blight. Removal of shoot strike may stimulate new shoot growth and further systemic infections. A late application of prohexadione calcium may slow this growth and reduce systemic infection. Do not tank mix prohexadione calcium with calcium sprays because calcium will reduce the effectiveness of prohexadione calcium. One pound of ammonium sulfate may be added for each pound of prohexadione calcium if the water source for spray applications contains high levels of calcium carbonate (hard water). Use a standard adjuvant/non-ionic surfactant.

Reynoutria sachalinesis extract of Giant Knotweed (Regalia) is a biofungicide that boost a plants natural defenses (induced systemic resistance). It can be applied as a foliar spray, dip, drench or drip irrigation meaning it protect the plants leafy tissue, flower, fruit, and root system. It works to control powdery mildew, fusarium, anthracnose, botritys, fire. Blight. It has a 0-day PHI.

Swinglea glutinosa extract (EcoSwing) is a botanical fungicide that acts by destroying fungal spores and mycelium through cell wall distruction which prevents the fungus from infecting the host plant. This product is labeled for the suppression of apple scab.