UMass Healthy Fruit -- Vol. 9, Issue 17: July 31, 2001

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Volume 9 -- 2001

Healthy Fruit is written by Jon Clements, Ron Prokopy, Dan Cooley, Arthur Tuttle, Gerald Lafleur, Wes Autio, Bill Coli, Duane Greene, Bill Bramlage, and Sarah Weis and is presented with the cooperation of New England Fruit Consultants and Polaris Orchard Management. 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.

Issue 17 - July 31, 2001

Summer Pruning Time
August marks the start of summer pruning time to improve red fruit color in apples. Pruning of vigorous, upright one- and two-year-old wood over the next few weeks can result in significant improvement of canopy light penetration, and therefore, better fruit color by harvest in September. Care must be taken not to remove or damage fruit. Pruning at this time will not affect cropping next year, and its overall effects on tree physiology are similar to dormant pruning. By removing leaf area at this time, however, fruit size at harvest may be reduced. Summer pruning can also aid spray penetration.

Orchard Musings
Recent orchard visits bring about the following orchard musings. Significant or not, it is up to you and your current orchard situation!

As noted on the label, Apogee (BASF Corp.) indeed appears to 'hang' more fruit compared to untreated trees. This can result in small fruit unless more aggressively thinned -- something to keep in mind if using Apogee next season.
Although the post-bloom freeze resulted in significant petal and seed browning, fruit set was better than expected in some frozen orchards. But, there appears to be a preponderance of small, poorly seeded (i.e., zero to one or two seeds per fruit) in these orchards. Despite conventional wisdom that these fruitlets would abort, they had staying power and will be problematic at harvest.
Poor tree growth in new plantings is an ongoing problem. Possible causes of poor tree growth include: poor quality nursery stock; inadequate site preparation and fertilization; drought; lack of pruning, training, staking; potato leafhopper, or other insect injury. Remember, new plantings are expensive! You need to push growth the first few years as hard as possible to get into production ASAP.
Foliar nutrient deficiency symptoms seem to be pronounced this year. Why? Could be stress (frost injury, heat, drought?) or simply insufficient nutrient application. If you have not done a leaf analysis -- including apples and peaches -- in any of your blocks for a few years, looks like this year might be a good time to do one to get a better handle on the nutrient status of your orchard(s).
Although not usually a problem here in MA, significant oblique banded leaf roller (OBLR) injury has turned up in an orchard where trees from Western New York were planted several years ago. OBLR is usually well controlled with organo-phosphate (OP) insecticides targeted at other pests, however, in New York and Michigan, significant resistance by OBLR to OP‚s has been noted. Perhaps this orchard has built up an endemic population of resistant OBLR‚s? Bottom line: always be on the lookout for unusual pests by scouting your orchard regularly!

Apple Maggot
AMF continue to invade orchards at a comparatively high rate. Captures on our baited and unbaited red sphere traps in unsprayed trapped blocks in several commercial orchards averaged about 4 times higher this past week than 2-3 weeks ago, and about 4 times higher than during the last week of July a year ago in the same orchards. These higher captures continue to signal that AMF are rather abundant this year. Growers should consider a total of at least 2 sprays against AMF, and possibly 3 sprays if late-ripening cultivars are a concern. There should be enough spray residue to protect Macs and Cortlands against AMF through late August, and Galas, Reds, Goldens and Fujis through early or mid-September.
So far, conditions have been favorable for a normal seasonal emergence pattern of AMF. But if the soil starts to dry out, emergence of adults becomes inhibited and will resume only after rainfall. In some years, that scenario has resulted in a late flush of emergers in the latter part of August or even September, and has led to considerable late-season injury. Let's hope for continued periodic rainfall, not only for better fruit size but also for a better chance of controlling AMF without having to resort to an extra late-season spray.

Mites
Most orchards have experienced few mite problems till now. But this past week, we have seen occasional blocks where red mites have flared and should be controlled to prevent serious bronzing. Pyramite is a very good rescue material, though it is more harmful to predators than Vendex. Unless the red mite problem is severe, Vendex (especially with the addition of summer oil) should result in satisfactory suppression.

Fall Webworms
At least a few ugly nests of fall webworms have shown up in almost every monitored orchard. If enough time and labor are available, direct removal of nests by hand is a safe and sure bet for control. If not, a treatment of the locally systemic material Spintor or Provado will do the job. Sprays of Guthion or Imidan against apple maggot should also work well.