SCAFFOLDS Fruit Journal, June 5, 1995

SCAFFOLDS Fruit Journal, Geneva, NY                Volume 4
Update on Pest Management and Crop Development      June 5, 1995

COMING EVENTS

                                                     43F       50F
Current DD accumulations (Geneva 1/1-6/5):           766       423
                       (Highland 3/1-6/5):           818       444

Coming Events:                              Ranges:
Spotted tentiform leafminer 1st flight subsides  489-978    270-575
American plum borer 1st flight peak              535-962    273-601
Codling moth 1st flight peak                    547-1326    307-824
Obliquebanded leafroller 1st catch              686-1059    392-681
San Jose scale 1st flight subsides              768-1058    434-648
European red mite summer egg hatch               773-938    442-582
Dogwood borer 1st catch                         798-1182    456-718


TRAP CATCHES (Number/trap/day)
Geneva:   
                                  5/22   5/25   5/30    6/1    6/5
Redbanded Leafroller               1.3    1.0    0.2    1.0      0
Spotted Tentiform Leafminer        202    108     63     42     29
Oriental Fruit Moth (apple)       10.9    9.5    2.1    3.5    0.8
Lesser Appleworm                  12.2   15.0    6.9    6.3    1.9
Codling Moth                       2.3    3.7    1.9   21.8    5.9
San Jose Scale                     0.1    1.0      0    3.5    2.3
American Plum Borer (cherry)       0.4    1.8    0.8    4.5    2.4
Lesser Peachtree Borer (peach)       0    0.3*   1.1    2.5    2.9
Lesser Peachtree Borer (cherry)      0      0    0.6*   3.3    3.0
Peachtree Borer                      0      0      0    1.3*   4.0


Highland (Dick Straub, Peter Jentsch)
                                  5/15   5/22   5/29    6/5
Redbanded Leafroller               0.7    0.6   <0.1      0
Spotted Tentiform Leafminer        8.2    2.6    0.5    0.9
Oriental Fruit Moth                1.0      0    0.5    1.1
Fruittree Leafroller               0.2      0      0      0
White Apple Leafhopper nymphs     <0.1      -   <0.1   <1.0
Codling Moth                      <0.1*   1.9    4.6    4.9
Lesser Appleworm                     -    1.0*  <0.1      0
Sparganothis Fruitworm               -      0      0    0.1*
Tufted Apple Budmoth                 -   <0.1*   1.1    1.4
                                                       * = 1st catch

PEST FOCUS
Geneva: Peachtree Borer 1st catch, 6/1.
Highland: Sparganothis Fruitworm 1st catch, 6/5; 1st Rose Leafhopper 
   adult on apple, 6/1.
Albion: Obliquebanded Leafroller pupae present, 5/31.
Lockport: Spotted Tentiform Leafminer sapfeeding mines present.

FRUIT DISEASE UPDATE

By:Dave Rosenberger, Plant Pathology, Highland

CEDAR RUST

Cedar rust lesions are now abundant on unsprayed trees where cedars were adjacent to the orchard. Cedar rust will continue to cause infections on terminal leaves for another 10-14 days if we have suitable infection periods. However, the window for fruit infection has passed for this season. Also, remember that cedar rust has no secondary cycle. Lesions on apple leaves produce spores that go back to cedar trees, but the spores from apple leaves cannot infect additional apple leaves.

WINTER DAMAGE

Occasional limbs on some apple trees are showing symptoms of winter damage that may have been incurred over the past several winters. The most frequent reports involve Empire trees, but in the Champlain Valley, McIntosh are also affected. The affected limbs leaf out slowly and produce mottled, leathery, narrow leaves that look a bit like leaves affected by primary mildew or like leaves affected by glyphosate herbicide. However, the affected leaves do not have the white mycelium on the surface that is present on mildewed leaves. I suspect that this injury is usually associated with basidiomycete fungi that have invaded winter-damaged limbs. Based on observation from previous years, I suspect that most of these affected limbs will "grow out" later in the season and will appear normal by the end of the season. However, severely affected limbs may die completely, and trees that show this symptom in one year sometimes show the symptoms again in subsequent years. With this disorder, there is nothing to be done except to allow the tree time to recover.

STONE FRUIT DISEASES

Despite a very cool bloom period, several growers have found brown rot in stone fruits that were not adequately sprayed during bloom. The long wetting periods apparently promoted infection, even though temperatures during wetting periods were nearly always below 60 F.

Peach leaf curl has been unusually severe in the Hudson Valley this spring. Contributing factors were that orchards were left unsprayed last year when we had no crop, and we had an unusually mild winter. In some cases, leaf curl was showing on more than 50% of the leaf canopy as of last week.

OBLIQUEBANDED LEAFROLLER

By:Art Agnello, Entomology, Geneva There are no reports of adult catches in the Hudson Valley or western N.Y. yet, but they're due any time now. Larval development is all over the place, as usual (everything from 3rd to 6th instars), and pupae were evident a few days ago (6/1) near Albion. It's not too late to hang a wing-type pheromone trap in problem apple blocks, in order to fix the date of first emergence in your specific area. Recall that we recommend sampling at 600 DD (base 43 F) after the first adult catch. It pays to keep an eye on the daily highs and lows for your area if you are doing your own trapping, in case our "normal" sampling date of July 5 turns out not to be accurate this year, especially considering the warm temperatures being forecast for this week.

oblique leafroller Larvae of the first OBLR summer brood cause two kinds of damage -- foliar feeding injury and rolling of the leaves, and more importantly, injury caused by feeding on the surface of the developing fruits. This fruit damage is usually more serious than the spring feeding by overwintered larvae, because more of the fruit injured late in the season remains on the tree at harvest. Despite the rather extreme measures some growers wage in the spring against the early generation larvae, you should remember that even an excellent control program against the overwintered brood does not eliminate the possibility of a problem summer population. To maximize the effectiveness of any sprays against the first summer generation OBLR infestation, you should sample leaf and fruit clusters at the proper time. You will need to know the date of the first adult flight in your area; the value of knowing the precise date of this event on your own farm cannot be emphasized too strongly, and maintaining a few pheromone traps is not very difficult or time consuming. Check traps two or three times a week until the first adult is caught. Wait for 600 degree-days (43 F base) after this date. Degree-day (DD) values can be obtained for some locations from CENET (from the "CLIMOD" Menu) or from Cooperative Extension personnel. You can also just look them up on the DD Charts that appeared in the March 20 Scaffolds, or else estimate them each day by using the following formula:

     Degree Days for 1 Day =  1/2  x  [Daily Maximum Temp. +                         
                      Daily Minimum Temp.] - 43.

If you do not have access to any of this information, use July 5 as an estimated best sample date in a "normal" year.

Guidelines for sampling can be found on pp. 77-78, 85-86, 89 and 94 of the 1995 Recommends. Sample from random trees that are representative of the entire block, examining 10 expanding leaf terminals per tree. It is not necessary to pick the terminals. Record the number of samples infested with live larvae; do not count actual numbers of larvae in an infested terminal, and do not count damaged terminals that have no OBLR in them, or those containing only dead OBLR. To minimize bias, choose half of your samples from inside the tree canopy, including some watersprouts, and the other half from near the outside of the canopy. If the tree is more than 10 ft tall, try to include some clusters from the mid- to upper canopy area. Use the 3% infestation threshold for fresh fruit, and 10% for processing fruit. A "Stop Sampling and Treat" decision means that a spray to control OBLR is recommended at this time. A "Stop Sampling, Don't Treat" decision indicates that you should return in 3-5 days, after 100 more degree-days have accumulated, and repeat the sample. A second "Below Threshold" decision indicates that no treatment against this generation of OBLR is recommended. Recommended materials include a B.t. product (such as Dipel, Biobit or MVP), Lorsban, Lannate, or possibly Asana or Penncap-M, depending on the population pressure in your orchards and the considerations discussed in the 5/30 article. We have a 2(ee) recommendation for Dipel plus a 1/10 rate of Asana, but please note that this strategy tends to be variable in its success rate from block to block. More on this pest in the next issue.

WORLD OF WORMS

Steve Hoying informs us of seeing unusually high populations of leaf-feeding caterpillars in young, non-bearing apple plantings this season. A quick inspection at one site turned up not only OBLR, but also other leafrollers, green fruitworms (more than one species), loopers, and gypsy moth larvae. The amount of defoliation this gang is capable of is often not tolerable by small trees that have little foliage to spare. Check your young plantings and apply something appropriate (at least Imidan or Guthion) if you find more than a nominal amount of leaf feeding taking place.

CODLING MOTH MODEL

As of today, 6/5, a total of 272 DD have accumulated in the Hudson Valley since the "1st adult catch" biofix; in Geneva, the value is 208. The recommended spray window to control 1st generation codling moth is 250-360 DD. The more problematic 2nd generation has a control window starting 1260 DD from the same biofix date; we will keep up our DD postings until that period has passed.

FEAR NO WEEVIL

Every year about this time, a bright metallic green snout beetle about 1/5" in length appears in apple orchards and strawberry fields, sometimes in considerable numbers. This weevil is most likely Polydrusus impressifrons, also called the leaf weevil; we've seen a few during the past week in western N.Y. It is of European origin and was first reported in New York in 1906. The larvae live in soil, where they feed on roots of various plants. The adult weevils feed on the foliage of many host plants, including birch, poplar, and willow, but also apple, pear, and strawberry. Leaf feeding is usually not extensive enough to justify special sprays. In commercial orchards, the normal cover spray program will take care of this problem. If the weevil appears in great numbers in a nursery, control using an OP may be necessary.

Scaffolds is published weekly from March to September by Cornell University -- NYS Agricultural Experiment Station (Geneva), and Ithaca -- with the assistance of Cornell Cooperative Extension. New York field reports welcomed. Send submissions by 3 p.m. Monday to:

Scaffolds Fruit Journal
Editors: A. Agnello, D. Kain
Dept. of Entomology, NYSAES
Geneva, NY 14456-0462
Phone: 315-787-2341 FAX:315-787-2326
E-mail: art_agnello@cornell.edu

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