Disease Management Update to 2000-2001 New England Apple Pest Management Guide

L. P. Berkett and T. Bradshaw

University of Vermont

 

Delayed First-Spray Strategy for Apple Scab

 

               The following “action threshold” for the first fungicide application when using this strategy was inadvertently omitted from page 13 of the guide:   “DELAY THE FIRST FUNGICIDE SPRAY UNTIL PINK OR UNTIL AFTER THREE INFECTION PERIODS (but before the 4th infection period), WHICHEVER COMES FIRST.”   Begin determining infection periods at green tip.

 

Notes on the Strobilurin Fungicides

 

               As indicated on page 85 of the Guide, both Flint and Sovran are only rated as “fair” in terms of efficacy against cedar apple rust.  If you have susceptible cultivars, moderate to high inoculum pressure, and conditions favorable for cedar apple rust and quince rust infection, you should not rely on the strobilurin fungicides for rust control.  If you do use Flint for cedar apple rust (or powdery mildew), the label states that you should alternate it (every other application) with a sterol inhibitor fungicide.

 

New Products

 

               Bac-Master (streptomycin sulfate): Equivalent to 17% Streptomycin (4-8 ozs./100 gal., see label for other rates).  Bactericide used to prevent fire blight.  Streptomycin is effective if used the day before, or the day of, a fire blight infection period.  Where fire blight is expected to be a problem, the first spray is made after blossoms open when weather conditions favorable for the disease are present or predicted within 24 hours.  Must be absorbed by the blossoms to be effective, should not be applied just before or during rain.  The frequency of repeat applications depends on weather, blossom opening and disease pressure.  Routine use of streptomycin to control shoot blight is not recommended.  However, application within 24 hours after the beginning of a hail storm is recommended for fire blight-threatened orchards.  Thorough coverage is essential for control.  Application of streptomycin at concentration greater than 6X is not recommended.  Restricted entry interval 12 hours.  Preharvest interval 50 days.

 

               Streptrol (streptomycin sulfate): Equivalent to 17% Streptomycin (4-8 ozs./100 gal., see label for other rates).  Bactericide used to prevent fire blight.  Streptomycin is effective if used the day before, or the day of, a fire blight infection period.  Where fire blight is expected to be a problem, the first spray is made after  blossoms open when weather conditions favorable for the disease are present or predicted within 24 hours.  Must be absorbed by the blossoms to be effective, should not be applied just before or during rain.  The frequency of repeat applications depends on weather, blossom opening and disease pressure.  Routine use of streptomycin to control shoot blight is not recommended.  However, application within 24 hours after the beginning of a hail storm is recommended for fire blight-threatened orchards.  Thorough coverage is essential for control.  Application of streptomycin at concentration greater than 6X is not recommended.  Restricted entry interval 4 hours.  Preharvest interval 50 days.

 

               Phostrol (phosphorus acid): Liquid formulation with the equivalent of 4.32 pounds phosphorus acid per gallon.  Foliar application for the control of Phytophthora spp. (Collar and root rot).  Systemic material.  See label for rates.  Restricted entry interval 4 hours.  Preharvest interval 0 days. 

 

 

Insect & Mite Update to 2000-2001 New England Apple Pest Management Guide

Ron Prokopy and Alan Eaton

University of Massachusetts and University of New Hampshire, respectively

 

 

New Products

 

               Avaunt (indoxacarb): 30% WG, 5-6 ozs./acre.  Registered for control of tarnished plant bug, plum curculio, codling moth, oriental fruit moth, lesser appleworm, leafrollers, apple maggot, and leafhoppers.  Maximum of 4 applications per year at no more than 24 ozs. total annual per acre.  Make no more than 3 applications prior to hand thinning.  No hand thinning after 4th application.  For best results, apply in 50-150 gal. water per acre and never more than 200 gal. water per acre.  Performs well against tarnished plant bug, plum curculio, some leafrollers, and leafhoppers.  Performance against apple maggot has been variable.  Avaunt represents a new class of compounds (oxadiazines) and is more toxic when ingested by insects than by contact alone.  Toxic effects are not immediate but gradual, sometimes requiring 3 or more days.  It is not systemic and does not protect new growth.  Does not redistribute readily on foliar surfaces once sprayed.  Residual activity lasts 7-14 days depending on conditions.  Safe on most beneficials.  Restricted entry interval is 12 hours.  Preharvest interval is 28 days. 

 

               Distance (pyriproxyfen): 0.86 lbs/gal L, 6 to 8 fl. ozs./100 gals. for aphid suppression on non-bearing trees; 8 to 12 fl.ozs./100 gals. for San Jose scale and spotted tentiform leafminer on non-bearing trees.  The active ingredient (same as Esteem) is an insect growth regulator, so it does not affect adult insects.  Restricted entry interval 12 hours.  Preharvest interval:  non-bearing trees only.

 

               Intrepid (methoxyfenozide): 80 WSP, 3-6 ozs./acre.  Registered for control of codling moth, lesser appleworm, leafrollers and leafminers.  Effective also against oriental fruit moth.  Maximum of 20 ozs. total material per acre per year.  Performs best in conjunction with an adjuvant to maximize deposition, redistribution, and weatherability.  Belongs to diacylhydrazine class of insecticides and has novel mode of action that mimics action of molting hormones of moth larvae.  Must be ingested by larvae to be effective.  Works best against internal feeders when application is just prior to egg hatch.  To avoid resistance, do not use against more than 3 consecutive generations of a pest.  Very safe on beneficials.  Restricted entry interval is 4 hours.  Preharvest interval is 14 days.

 

               Valero (cinnamaldehyde): 30%L, 1-9 gals/acre.  Registered for control of aphids and spider mites.  Label recommends a phytotoxicity check before treating, to ensure that treatment is safe for your varieties. Experience with products that have this ingredient (but used in greenhouses) suggests that it loses effectiveness several weeks after being opened.  Cinnamaldehyde is a component of cinnamon, the ground inner bark of certain tropical trees in the laurel family.   Spray water should have a pH of 3.5 to 7.5, or product degradation may result. Restricted entry interval is 4 hours.  Preharvest interval is 0 days.

 

 

Changes in Labels of Other Registered Compounds

 

               Lorsban:  Effective as of December 31, 2000, the use of Lorsban 4E and Lorsban 50W on apples is restricted to pre-bloom applications only.  EPA recently amended that by approving supplementary labels for both products (3/15/01) that allow application of these materials to the lower trunk only (for borers) after bloom.  These supplemental labels now go to each of the New England states for approval.  There are several restrictions on these supplemental labels, which are aimed at avoiding any post-bloom spray contact with the foliage or fruit.