Insects | Credits
Volume 6, No. 10 May 27, 1997
43F 50F Current DD accumulations (Geneva 1/1-5/27): 426 192 (Highland 1/1-5/27): 647 315 Coming Events: Ranges: Apple grain aphid present 137-496 67-251 Spotted tentiform leafminer 1st flight peak 180-544 65-275 San Jose scale 1st catch 189-704 69-385 Lesser peachtree borer 1st catch 224-946 110-553 Oriental fruit moth 1st flight peak 259-606 96-298 Spotted tentiform leafminer sap-feeders present 295-708 123-404 European red mite 1st summer eggs 448-559 235-320 Pear psylla hardshells present 463-651 259-377 McIntosh at petal fall 418-649 210-340 Phenologies (Geneva): Apple (McIntosh) - 50% Petal Fall Apple (Red Delicious) - Bloom Pear (Bartlett) - Petal Fall Sweet Cherry (Windsor) - Fruit 10 mm Tart Cherry (Montmorency) - 50% Petal Fall Plum - Petal Fall Peach - Petal Fall PEST FOCUS Geneva: 1st Codling Moth trap catch 5/27. (1st catch in Highland was 5/19.) Degree days base 50 F accumulated since the biofix, for use in the Michigan model to determine the best time for a control spray, will be reported weekly, beginning with the next issue. Highland: 1st European Red Mite summer eggs observed. 1st Plum Curculio and European Apple Sawfly scars observed. TRAP CATCHES (Number/trap/day) Geneva: 5/12 5/15 5/19 5/22 5/27 Green Fruitworm 0.1 0 0 0 0 Redbanded Leafroller 0.9 2.2 2.3 0.2 0.8 Spotted Tentiform Leafminer 456 618 499 164 439 Lesser Appleworm 0.6 10.3 7.6 8.3 4.8 Oriental Fruit Moth (apple) 0 0.8* 0.8 1.7 0.6 Oriental Fruit Moth (peach) 0 0 0.1* 0 0 San Jose Scale 0 0 0 0 0 Codling Moth - 0 0 0 0.4* American Plum Borer 0 0 0.4* 0 0.1 Highland (Dick Straub, Peter Jentsch): 4/28 5/5 5/12 5/19 5/27 Green Fruitworm 0.6 0.1 0 0 0 Redbanded Leafroller 18.1 18.8 5.9 3.2 0.4 Spotted Tentiform Leafminer 49.7 53.2 41.8 28.6 3.5 Oriental Fruit Moth 0.6* 3.0 3.2 4.2 0.4 Lesser Appleworm - - 0 0.3* 1.1 Codling Moth - - 0 0.3* 1.6 * = 1st catch
by Art Agnello and Harvey Reissig
Whether it's an effect of the brisk temperatures during the past month,
or only the unknown vagaries of population dynamics that govern OBLR incidence,
leafroller numbers and general infestation levels are not quite up to their
normal speed yet, and even specimens from our never-fail hot spots seem
uncharacteristically tiny and inauspicious so far (that should rile the
worm gods if anything will). The economics of controlling the overwintered
brood don't always justify the small amount of early season damage prevented,
but we know that some growers like to establish a presence against the
summer generation by including a material in the petal fall spray to do
what they can against susceptible larvae. For problem blocks, we would
recommend Dipel, Lorsban or Lannate (in order of increasing harm to predator
mites), together with the usual advice to be timely with summer brood sprays
when they become necessary.
Apples showing early season obiquebanded leafroller feeding damage
Speaking of which, we haven't yet heard anything official, but we expect the Section 18 application for Confirm to be "acted upon" (EPA's words) quite soon, and we hope favorably, which would be in time for use against the July brood that causes the most problems. Last season's experiences with Confirm in N.Y. actually ran the gamut from very acceptable to anything but, and it's clear that even though this product will never be the silver bullet the industry has been looking for, it can be a valuable alternative to our other chemical choices if used wisely. Harvey Reissig did extensive field tests with Confirm last year, and we have continued our talks with other apple researchers as well as the people at Rohm and Haas about the best strategy for using this product when it becomes available. There will be more testing this summer, but for the time being, the following points represent our consensus of the best way to proceed with Confirm, which is (we would reiterate) a very different kind of leafroller material than any other we've worked with before:
Mature obliquebanded leafroller larva
For situations where European red mite pressure or the crop's sensitivity to them doesn't necessarily justify the expense of an early season treatment with Agri-Mek, Apollo or Savey, this is the time of year when a summer oil program might be considered as an alternative preventive approach. Field research trials conducted in commercial and experimental apple orchards in western N.Y. during the past few years have shown the effectiveness of using a highly refined oil in a seasonal program to control mites throughout the summer. Some examples of these products are Sunspray Ultra Fine Spray Oil (Sun Refining & Marketing, Philadelphia), and Stylet-Oil (JMS Flower Farms, Vero Beach, FL); others are labeled and may be available, although we haven't tested all brands.
Our approach is to make three applications, on a preventive schedule, immediately after the bloom period, before mite populations have a chance to build. The first application can be any time from petal fall to 1-2 weeks later, followed by two additional sprays at 10-14 day intervals. The oil is not concentrated in the tank, but rather mixed on the basis of a rate per 100 gallons of finish spray solution; for instance, at the 1 gal. rate, a spray tank holding 500 gallons receives 5 gallons of oil. The sprays are applied at a volume sufficient to obtain adequate coverage of the canopies; in most cases, we recommend 100 gal. per acre. Dosages that we have tested are 6.5 oz., 1 qt., and 1, 2, and 3 gal./100 gal. of finish spray solution. Results of our tests can be summarized as follows: the 2 and 3 gal. rates effectively controlled mite populations for the entire season in all but the most extreme cases; the 1 gal. rate maintained control of moderate populations but was not effective against severe mite pressure (a fourth spray was necessary later in July); and the lower rates provided only minimal control (light population pressure), permitting unacceptable mite numbers by mid-July in orchards with moderate or severe populations.
Bronzed appearance of severely damaged apple foliage, left, and healthy foliage, right
One undesirable consequence of the oil treatments can be the occurrence of small necrotic lesions on some of the leaves in blocks receiving the highest rates, particularly 2 and 3 gal. Foliar injury tends to occur mainly in those portions of the canopy where the spray has dried unevenly or else accumulated after the application, especially in locations adjacent to the sprayer and at the ends of leaf terminals. However, the oil caused no leaf drop in our tests, even in cases where the trees were under moisture stress. Fruit samples taken at harvest to check for any effects on fruit quality showed no differences in fruit color between oil-treated and untreated apples in a range of varieties. Also, there was no evidence of other anomalies such as a roughened surface, raised lenticels, or finish problems in the treated fruits. The only adverse result was an increase with oil rate of a varietal stippling characteristic in the skin of Red Romes, known as "scarf". Certain other varieties, such as Stayman, Jonathan, and some Red Delicious strains, also exhibit this characteristic to some degree, but the oil tended to make it worse in our trials. Related tests we conducted using handgun oil sprays gave encouraging indications that summer oil sprays may be as effective against motile stages of mites as it is on the eggs.
Overall, the results of this work demonstrate that summer oil applications can be used to effectively control European red mite populations in many orchard situations. So far, mites have not demonstrated an ability to develop a resistance to oil, and oil is less toxic to at least some beneficial species than are traditional toxicants. Although it is possible to kill some predator mites by directly spraying them, overall mortality is not very high. In general, the most important predator mites respond to oil sprays with a temporary population decrease, but their long-term survival is not seriously hampered. Some potential drawbacks to this management strategy are:
Principles to guide its use:
European red mite summer eggs on leaf
We haven't yet seen evidence that psylla numbers are on the rise in most pear orchards in western N.Y., but the 1-2 nymph/leaf threshold we consider appropriate for an Agri-Mek application could be approaching in some parts of the Hudson Valley. This should be the week designated as a suitable time to begin those sprays where this product is elected, with western N.Y. orchards starting to come due by next week. Tree condition appears to be good, so foliage should be succulent enough to absorb the material. We would reiterate our recommendation to use the high rate of 20 fl. oz. of product mixed with 1 gallon of Ultra Fine oil per acre, to maximize the treatment's effectiveness.
CHERRY FRUIT FLIES
No adults have been reported caught on sticky board traps yet, but because of the zero tolerance in cherries for insect damage or presence, it's prudent to begin sprays in your cherries now (for this pest as well as for curculio). Guthion, Imidan (tart cherries only), Sevin, the synthetic pyrethroids, or Penncap-M are all effective treatments. Sevin, Imidan and Penncap-M will also control black cherry aphid.
Cherry fruit fly adult
Cherry fruit fly maggot feeding inside of fruit
External damage to fruits infested with cherry fruit fly
LESSER PEACHTREE BORER
Remember to get your trunk and scaffold sprays on peaches and cherries during the first week of June if borers are a problem in your blocks. This pest increases the severity of Cytospora canker infections in peaches and is often found within the canker; by feeding in the callous tissues, it interferes with the tree's natural defenses against the disease. Infestations can be determined by the presence of the insect's frass, which resembles sawdust, in the gum exuded from the wound. In peaches, you can use Lorsban, Thiodan, Asana, Ambush, Pounce, or Penncap-M for this application. In cherries, use Lorsban 4E, Thiodan 50WP, Asana, or Ambush 25WP as a trunk spray ONLY; do not spray the fruit.
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
Department of Entomology, NYSAES
Geneva, NY 14456-0462
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Photographs courtesy of New York State Integrated Pest Management Program