Healthy Fruit #5
Prepared by the University of Massachusetts Apple IPM Project Team in cooperation with New England Fruit Consultants and Polaris Orchard Management
Slow and steady blossom development is the rule across the state.
Temperatures have not been excessively warm, and depending on whether
you're still suffering the effects of the April Fool's Surprise, it
hasn't been too cold either. With any sort of warmth, trees will be
in bloom next week at this time.
So far, the weather has not been favorable for tarnished plant bug activity and trap captures are reflective of low levels of activity in almost all orchards. In one orchard though, trap capture levels are at 8 TPB per trap, which is well over the threshold recommended for consideration of treatment. Unfortunately, the low trap captures to date do not necessarily mean that TPB are finished for the year. Given a few successive warm days during bloom, TPB can cause substantial damage to the fruit. The damage during bloom looks less like the common dimpling of the fruit and has more of a scabby appearance, similar to curculio damage.
Monitoring traps have very little capturing
power for TPB as soon as white tissue begins to show in blossom
clusters. This is the case because the white tissue of the clusters
competes with the visual stimulus of the white rectangle monitoring
traps. These monitoring traps are not a good indicator of TPB
population densities after mid-pink. Growers who traditionally have
problems with dimpling and scabbing of fruit by TPB should visually
inspect blossom clusters at late pink and into bloom in order to
determine whether or not there is a level of damage which warrants a
petal fall insecticide application.
This year, there is a considerably greater
number of orchards with leafminer trap captures which exceed
treatment thresholds than last year. Many of these orchards have
reached 50 LM per trunk trap, which is a sure sign that some action
needs to occur at petal fall or soon after. Last week's issue of
Healthy Fruit contains recommendations for LM management.
European red mite eggs have hatched in
orchards which are at early pink or later. Although an oil
application in the early stages of egg hatch will still be effective
against remaining eggs, the benefits of oil applications against
mites begin to decrease substantially after egg hatch has begun.
In the earliest orchards, EAS have already
been captured. Now (mid- to late pink) is the time to hang white
sticky rectangle monitoring traps for sawfly. These traps should be
hung as high as you can reach on the south side of the tree canopy,
clear of any waving branches.
In orchard blocks which have not received any oil applications, psylla nymphs are abundant in blossom clusters. Growers observing large numbers of nymphs in clusters should be prepared for a post-bloom insecticide application. Of the post-bloom treatment options, Agrimek has shown good control of psylla when applied 10-15 days after petal fall. Provado is now labeled for use on pears and has shown promise in reducing high populations, but the limited residual control (10 days or so) makes it best suited as a late-season application. With proper timing, Mitac is also effective as a post-bloom treatment for psylla. For growers who are considering a treatment of Mitac, New York recommends back-to-back sprays after petal fall, with one application about two weeks after petal fall and the second application 7-10 days later. For a more complete discussion of recommendations for psylla management, refer to this year's issue of the March Message.
What else is there to say? We are in the
middle of apple scab season, and now is not the time to take chances.
Wait until a week after petal fall to reevaluate the scab situation,
and in the meantime, maintain a tight protective and/or
post-infection schedule.
As the time to apply copper has long past, the remaining option for those who are concerned with fireblight is streptomycin, sold as AgriMycin. Jim Johnson, of Merck, asked me to pass this on.
A recent audit of our inventory for Agri-mycin (streptomycin sulfate) 17 and Mycoshield (oxytetracycline) revealed that some growers may have product that currently is likely to be out of specification.
We maintain a strictly specified range of percentage of active ingredient for these products and we have found that some of our own retained samples currently contain slightly less than the minimum specified amount of the active ingredient. Although the products fully conformed to specifications at the time they were manufactured and sold, the active ingredients may have naturally degraded over time.
Please contact Dr. Jim Johnson, Merck Technical Services, at (517)
676-0884 (email:
james_agvet_johnson@merck.com),
should you have any questions.
Bills to provide IPM funding have been proposed in both the national Congress and the Massachusetts legislature.
In Massachusetts, the proposal would move IPM funding from the Dept. of Food & Agric. to the University, a move which would provide nearly $100,000 more available money, thanks to savings in overhead and fringe benefit charges currently made on the DFA based line in the budget. In addition, the a basic funding increase has been proposed. Both actions will either be passed or defeated by May 15.
In Congress, a bill to provide nearly $15 million in extra IPM
funds is being considered. This funding, and an increase in the
present Massachusetts funding, are badly needed by the UMass IPM
program, since approximately $250,000 in special grants available
over the past 6 years has been discontinued.
Healthy Fruit is written by Dan Cooley, Ron Prokopy, Starker Wright, and Wes Autio, except where other contributors are noted. Final copy is edited by Dan Cooley. Publication is funded in part by the UMass Extension Agroecology Program, grower subscriptions, and the University of Massachusetts IPM Program. Please cite source if reprinting information.