PGR Proceedings Procured

This, from PennState pomologist George Greene, sounds like a worthwhile investment. I will have a copy in the office too if you'd like to borrow. JC
Horticultural specialists from the Eastern US brought their expertise to Adams County Pennsylvania on March 16, 2001 at the Penn State Tree Fruit Plant Growth Regulator School. The intensive all day workshop provided approximately 90 growers with the latest research and techniques for using plant growth regulators. Topics included:

- The basics on thinning chemicals for apples
- The NC thinner combination table
- Some aggressive thinning programs that have worked for me
- My experience with combinations of thinners
- Massachusetts thinning strategies
- What weather to watch when planning thinning applications
- PA Spray patterns - The good, the bad and the ugly
- Critique of some PA Spray Patterns
- A model for assessing thinning program success
- Apogee® - Grower assessment of 2000 use
- Apogee - Provide Antagonism
- ReTain - a harvest management tool
- MCP - A quality retention PGR for stored apples

A 225 page proceedings notebook is available for purchase at a cost of $20.00 per copy. Requests for the notebook can be made to:

Laurie A. Roth
Extension Agent-Tree Fruit
Penn State Cooperative Extension - Adams County
670 Old Harrisburg Road Suite 204
Gettysburg, PA 17325
(717) 334-6271
E mailto: lar19@psu.edu

Peach Pruning Principles

Most everyone is finished apple pruning, and for those who have them, it is now peach pruning time. Keep in mind the goals of open-center peach pruning, which are: remove old, slow-growing, non-fruitful shoots; prune-out approximately one-third of the tree to promote new growth; keep the fruiting zone low so all fruit can be harvested from the ground; open the center of the tree to promote air circulation (disease control) and light penetration (fruit color); and remove diseased or dead shoots, rootstock suckers, and water shoots.

Here is a short article on peach pruning by Cornell Cooperative Extension's Steve Hoying which appeared in the May 1997 Fruit Growers News.

Now that peach bloom is here it is time to go to work pruning.

Peaches should be pruned at bloom or soon after so that pruning can be adjusted to remove a portion of the crop that would require expensive hand thinning later. In other words use your pruning to help with the thinning.

The second reason to prune at this time is to lessen the detrimental effects of Cytosphora canker for which there is no chemical control. By pruning in bloom wounds can heal quickly closing out the fungal spores. This fungus is very active during cooler conditions so pruning after it starts to warm up will lessen the chance of infection.

Most peach orchards are started with an open center type pruning. It is important to maintain strong disease-free scaffolds so first remove all the small winter killed twigs along these scaffolds completely. At the same time remove all dead, damaged and diseased wood throughout the canopy. Especially limbs with severe canker should be completely removed. Canker removal should be considered if on main scaffold limbs. Remove strong upright suckers and useless hangers.

Next limit the tree's height. Keep trees low and easy to care for by limiting the height to what you can prune using a long handled pair of lopping shears. Limbs taller than you can reach is too tall. This is best done using bench-type cuts to strong outwardly growing laterals off last year's limbs.
Remember that unlike apples and cherries, peaches are grown on one-year-old wood, so strong heading cuts should be used to encourage the production of new one-year-old wood. If trees have gotten too tall they can be severely pruned to a lower height. This does reduce or eliminate crop the year of pruning so it is best done in wipe out or low crop years.

Finally thin out remaining wood to balance crop load and stimulate new fruit bearing wood production.
Newly planted trees should be headed to 24 inches in height. Side branches can be left since there are few adventitious buds. Be sure and stub side branches leaving three to four stubs.

Organic Apple Workshop Slated

An all day Organic Apple Workshop is scheduled for April 21 at Saratoga Apple in Schuylerville, NY (near Saratoga Springs). The Workshop will be lead by Michael Phillips (author of The Apple Grower: A Guide for the Organic Orchardist) and is sponsored by the Albany, NY based Regional Farm and Food Project. There is a registration fee and you need to contact the Project (518-427-6537, or 426-9331) if you'd like to attend.

Bud Development

There's quite a range in developmental stage of apple buds. As of April 16, buds in the most southern orchards of Massachusetts were at early green tip, buds in eastern orchards were at silver tip and buds in the hill orchards of western Massachusetts were still dormant. The slow rate of bud development is good news for all who still are pruning and trying to chop or move the accumulated brush.

Plant Bugs

For several consecutive years, tarnished plant bugs (TPB) have been substantially fewer than in years previous. Most but not all growers have escaped economic injury from this pest that used to account for more culled fruit in wholesale packing lines than any other insect pest. Principal reasons for this decline are likely the establishment of plant bug parasitoids released in New England several years ago together with a decline in the amount of alfalfa associated with the declining dairy industry. Alfalfa is a favorite host plant of TPB during autumn and a source of lots of overwintering adults.

The generally low numbers of TPB in recent years do not guarantee that any given orchard will be free of TPB injury. As a safeguard, we still recommend that growers or their consultants set out white rectangle TPB traps at silver tip (no later than green tip). As in the past, traps should be hung at knee height, clear of waving branches and tall grass. Thresholds and optimum timing of insecticide treatments are given in the New England Apple Pest Management Guide. Traps are available from Orchard Equipment and Supply in Conway, Great Lakes IPM and Gemplers.

Leafminers

As we reported in the March Message, there's a big change underway in the composition of species of leafminers inhabiting Massachusetts orchards. A decade ago, virtually all orchards were dominated by apple blotch leafminers (ABLM). Last year, 75% of orchards we sampled were dominated by spotted tentiform leafminers (STLM). ABLM tend to emerge earlier than STLM and tend to accumulate on tree trunks (a heat sink) more so than do STLM.
Sticky red rectangle traps stapled to tree trunks at green tip or half-inch green have proven quite reliable for determining abundance of ABLM and predicting need for treatment of first-generation ABLM. We have less faith in these trunk traps for assessing population levels of STLM. Even so, captures on trunk traps can give a general idea of whether you have a few, a moderate number or a lot of leafminers, despite our lack of confidence in using capture thresholds as a basis for treatment need against STLM. Red trunk traps are available from the same sources that supply TPB traps.

Mites

Good news on the mite front, at least at the start of the growing season. Hope we can say the same in July. We sampled about a dozen orchards in various parts of the state last week and could not find any mite eggs, even on mite prone cultivars. None of the growers who attended last weeks twilight meetings reported any problem with pickers having orange hands last fall. This would have been a sign of overwintering European red mite (ERM) eggs in the calyx end of fruit. So it seems that just as we entered last spring, we are entering this spring with comparatively low numbers of overwintering ERM eggs. Just as last year, many growers may be able to achieve acceptable season long control of ERM with use of oil alone.

As always, we are placing a strong emphasis on recommending use of early-season oil applications as the foundation for a sound mite management program. We remain firm in the belief that use of oil sets the stage for effective management of mites. Much evidence of resistance to Apollo and Savey has been demonstrated (in other countries) where these materials have been used for 3 or more consecutive seasons. Both materials are safe on beneficials, but are essentially interchangeable in development of resistance. Given the fact that use of both materials has become fairly widespread since registration several years ago, eventual resistance development is likely – leaving both as short-term solutions.

Our philosophy at present remains: a pre-bloom oil program is the best start to successful long –term mite management. If wind, cold, and traction are favorable, we recommend use of a 2% oil spray at or near half-inch green, followed by a 1% oil spray as a supplemental treatment.

Pear Psylla

No egglaying seen yet. So there's still time for mounting the first line of defense against this often troublesome pest: oil spray. Oil is an effective approach to prebloom suppression of egglaying by acting as a deterrent to ovipositing females. It also tend to suffocate eggs that have already been laid. As recommended by Art Agnello in New York, oil rates depend on when you start. If buds are still dormant, one spray of 3% oil or two sprays of 2% oil through green cluster will work. If buds are swollen, one spray of 2% oil or two sprays of 1% oil up to white bud should do fine. The rationale of using oil spray lies in delaying the timing of any needed insecticide spray until as late as possible. If 2001 is like 2000, pre-bloom oil alone may be enough to provide good season-long control of psylla.

Scab Lab

Scab spores collected on April 17 in Amherst and examined by squash mount evaluation were not mature, but if we get warm weather during the week to come spore development is imminent. Once maturity is reached, it doesn't take much heat before the spores will discharge with the next rain. Reports from the Hudson Valley (Highland, NY, Dave Rosenberger), where 23% of the scab spores were mature on 4/11, state that large numbers of ascospores are ready to go with the next rain. We are not quite there, especially in orchards that are higher and cooler than Amherst, but orchards in southern and eastern MA had best be ready to protect vulnerable plant tissue if we get warm and wet weather over the next several days. A protectant fungicide such as copper, mancozeb, captan , or Polyram at green tip is advised, especially in blocks that had scab last year. Scab development seems to be a little ahead of tree development at most sites, indicating that early infection periods could be more significant than usual this year.