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Any scab that is going to show is now showing. If you only look for scab once a year, now is a good time to do it.
It seems that the places that have significant scab this year had significant scab last year. A bad scab problem last year hasn't always come through again, but if you had scab last year and think you squeaked through this spring, you may want to look again just to be sure.
The heat we've had recently is as good an ally as there is for fighting scab that is in the orchard. Temperatures over 80 F combined with an eradicant fungicide will do what you want - stop spore production and prevent new infections.
Captan should be a part of any eradication program. Full rates of captan applied a couple of times 5 to 7 days apart in the heat will both protect fruit and foliage from new infections and eradicate the existing infections. Benlate, Topsin M or Syllit are also good eradicants where they have used sparingly. In all cases, they should be combined with captan for maximum effect and resistance management.
As the days stay hot, and tissue matures, the chance that a scab infection will spread goes down. But make a mental note that if you have had a couple of years of scab in a block, you may want to take action this fall and early spring to knock down the inoculum. It's a lot easier to manage scab in a "clean" block than a it is in one where the fungus has taken up long-term residence!
Plum curculio injury in commercial orchards has remained extremely low, despite weather patterns that are highly favorable to PC activity. Across our most recent samples, damage in managed blocks statewide has flatlined at 0.2%, the lowest levels in recent memory. At this point, most growers are likely considering whether a treatment against late-arriving PC is necessary, as damage has been known to occur on fruit as large as 1 ½".
In blocks of unmanaged trees (with the heaviest PC infestation around), immigration has not picked up in the last week, indicating that few PC remain to invade. Though few new PC have arrived of late, those present in blocks without chemical control have been very active: damage has risen from 69% (5/31) to 100% (6/6). Even with cooler weather in store for the next couple of days (6/9-6/11), the New York degree-day model predicts that the PC season will likely end this weekend. Taken together, these data suggest that if an active residual cover is in place that will last through the weekend, an additional treatment will not be necessary. In orchards where residual coverage will not endure the week, or in areas prone to late PC injury, a final border application may be warranted, targeting perennial hotspots.
Over the past two seasons, the general pattern of leafminer infestation is something of a mystery. Many growers were caught by surprise toward the end of last season by an explosion of third generation mines, which translated into a very heavy early-season population this year (trap captures exceeded 3000 LM per trap in some orchards). However, despite all factors (except one) favoring early buildup of LM, presence of first-generation mines on leaves has been light thus far.
In commercial orchards, we assume that the major factor thwarting rapid buildup of LM is the effectiveness of properly timed chemical controls. Provado was the material of choice in most orchards, and control of first-generation mine development has been excellent. In orchards where no LM treatment has been applied yet and mines are exceeding threshold levels, growers are advised to wait for the second generation to gain control, as little can be done to manage tissue-feeding mines. Although timing applications is generally more difficult, second-generation control (usually in late June) can be achieved through use of Provado, Lannate, or Agri-Mek.
Eggs of the first summer generation of red mites have begun to hatch in many sites, but most monitored blocks remain relatively free of mite pressure. At this point, it is late for use of Agri-Mek or Vendex, and is getting so for institution of a summer oil program. Use of summer oil can offer reasonable control of ERM, and periodic use of such a strategy certainly contributes to resistance management. However, there are a few drawbacks, most notably incompatibility with captan, the most common control for summer diseases.
If an oil program is not possible, mid-season control can be gained through use of one of the labeled rescue materials: Carzol, Kelthane, Pyramite, or Apollo. As has been the case for many years, we do not recommend consistent use of either Carzol or Kelthane due to harsh effects on predators (Carzol) and rapid development of resistance (both). Pyramite and Apollo are likely the best available options for use as a summer treatment; the developing mite situation should be assessed in late June before determining if such an application is necessary.
Over the past several years there has been increased attention paid to borers of several species as potentially problematic pests of both apples and peaches, particularly in low-spray orchards. In recent years, the region has reported increases in sightings of roundheaded appletree borer, dogwood borer, twig-boring apple pith moth, and lesser peachtree borer.
Prevention remains the best management tool in dealing with borers; if a reduced-spray approach is being used, every effort should be made to practice cultural techniques which will reduce the threat of infestation. Preventive measures include periodic examinations of mouseguards for hidden borer activity, control of burr knots, removal of host plants from the orchard perimeter (apple, hawthorn, shadbush, and mountain ash are the most common), and meticulous management of the orchard floor. Lack of cover at the base of tree trunks not only discourages borer egglaying, but also allows access to larvae by woodpeckers, which are the predominant natural predators of trunk-boring insects.
During peak emergence, usually between mid-June and early August (depending on the species), a trunk and scaffold application of Lorsban or Thiodan (Asana, Ambush, Pounce, and Penncap-M are also labeled) should provide good control of the adult borers. If evidence of larval infestation is seen (small holes with sawdust, often associated with gumosis on peach), then efforts should be made to kill the larvae before damage to the trees is permanent. Unfortunately, larvae are best controlled the old-fashioned way: inserting a wire or awl into their hole, or digging them out with a knife. Any trees within the orchard that are irreversibly damaged should be removed from the orchard completely to prevent further infestation.
Healthy Fruit is written by Dan Cooley, Ron Prokopy, Starker Wright, Wes Autio, and Duane Greene except where other contributors are noted. Edited by Dan Cooley. Publication is funded in part by the UMass Extension Agroecology Program, grower subscriptions, and the University of Massachusetts IPM Program. A text version can be e-mailed to you if you contact Doreen York. Please cite this source if reprinting information.
