July 6, 2004 Volume 13 No. 16 Update on Pest Management and Crop Development
* = 1st catch
Geneva: Obliquebanded leafroller flight began 6/7. Sampling should take
Highland: Apple Maggot
fly numbers increasing/above threshold.
Oriental Fruit Moth
Spotted Tentiform Leafminer
Oriental Fruit Moth
Spotted Tentiform Leafminer
Oriental Fruit Moth. This pest's development is tracked using a 45°F DD model from biofix, defined as the first sustained moth catch. We are currently just into the start of the second brood, which started about June 30 in WNY. Pesticides to control this brood should be applied at 175-200 DD after this date. Our sample numbers as of today:
Codling Moth. We are currently between the first and second brood control windows for this pest. With 1260 DD (base 50°F) from the 1st catch of the season as a first spray date for the second brood, we currently have:
Obliquebanded Leafroller. 25% egg hatch is predicted at 450 DD (base 43°F) from the 1st catch, with 50% egg hatch at 630 DD. Our sample numbers so far:
A number of orchards have begun to show infestations of foliar pests now, some of which tend to increase in response to the "flush growth" that is caused by the frequent showers and adequate moisture that we have experienced this season. Green aphids are more plentiful in the Hudson Valley so far; potato leafhoppers were very early there and are showing up now in western NY. No doubt all growers in all our regions would do well to keep an eye on local populations.
Green Aphids: Apple aphid, Aphis pomi, Spirea aphid, Aphis spiraecola
Although small numbers of these aphids may be present on trees early in the season, populations generally start to increase in mid- to late June. This trend has been delayed somewhat by the cool spring weather this year, but our early plentiful rains and predicted heat should soon provoke a respectable amount of the succulent terminal growth much favored by these insects. Large numbers of both species may build up on growing terminals on apple trees during summer. Both species are apparently common during the summer in most N.Y. orchards, although no extensive surveys have been done to compare their relative abundance in different production areas throughout the season.
Nymphs and adults of both species suck sap from growing terminals and water sprouts. High populations cause leaves to curl and may stunt shoot growth on young trees. Aphids excrete large amounts of honeydew, which collects on fruit and foliage. Sooty mold fungi that develop on honeydew cause the fruit to turn black, reducing its quality.
Aphids should be sampled several times throughout this season starting in late June. Inspect 10 rapidly growing terminals from each of 5 trees throughout the orchard. Record the percentage of infested terminals. No formal studies have been done to develop an economic threshold for aphids in N.Y. orchards. Currently, treatment is recommended if 30% of the terminals are infested with either species of aphid, or at 50% terminal infestation and less than 20% of the terminals with predators. An alternative threshold is given as 10% of the fruits exhibiting either aphids or honeydew.
The larvae of syrphid (hoverflies) and cecidomyiid flies (midges) prey on aphids throughout the summer. These predators complete about three generations during the summer. Most insecticides are somewhat toxic to these two predators, and they usually cannot build up sufficient numbers to control aphids adequately in regularly sprayed orchards. Check Tables 5 (p. 54) and 12 (p. 61) in the Recommends for toxicity ratings of common spray materials. Both aphids are resistant to most organophosphates, but materials in other chemical classes control these pests effectively, including Asana, Danitol, Dimethoate, Lannate, Provado, Thiodan, Vydate and Warrior.
Potato leafhopper (PLH), Empoasca fabae
PLH is generally a more serious problem in the Hudson Valley than in western New York or the Champlain Valley. PLH does not overwinter in the Northeast but instead migrates on thermals (warm air masses) from the South. Adults usually reach the Hudson Valley by May or early June and are found from mid- to late June in western New York. Because PLH migrate constantly during the season, there are no distinct broods or generations and the pest may be present continuously in orchards from June through harvest.
PLH feeds on tender young terminal leaves. Initially, injured leaves turn yellow around the edges, then become chlorotic and deformed (cupping upward) and later turn brown or scorched. Damage is caused by a toxin injected by PLH while feeding. PLH also occasionally causes symptoms similar to the effects of growth regulators, such as excessive branching preceding or beyond the point of extensive feeding. PLH damage is often mistaken for injury caused by herbicides, nutrient deficiency, or overfertilization. PLH injury may not be serious on mature trees but can severely stunt the growth of young trees.
Nymphs and adults should be counted on 50 to 100 randomly selected terminal leaves in an orchard. Older trees should be sampled approximately every three weeks during the summer. Young trees should be sampled weekly from early June through July. PLH nymphs are often characterized as moving sideways like crabs, whereas WALH generally move forward and back. No formal studies have been conducted in New York to determine the economic injury level for PLH on apples, so we suggest a tentative threshold of an average of one nymph or adult PLH per leaf.
Little is known about the natural enemies of PLH, but it is assumed that they cannot control this pest in commercial New York orchards. Populations of PLH in New York are resistant to the conventional organophosphate materials. The list of effective materials is similar to that given for aphids, with the addition of Avaunt.
Apple rust mite (ARM), Aculus schlechtendali
The wedge-shaped adult has two pairs of legs at the front of its body and is brownish yellow in color. These mites are invisible to the naked eye, requiring a minimum magnification of 15X to be observed.
This species attacks apple primarily. Yellowish brown leaf discoloration occurs under very populated conditions (hundreds per leaf), sometimes accompanied by silvery-white blotches. Browning of the lower surface and drying out of the leaves occur as well. In serious infestations, they may occasionally russet fruit.Under most circumstances, growers will not notice an infestation until leaf damage has occurred, and populations generally taper off by midsummer anyway. As a means of prevention, preserve mite predators. Miticides are of questionable value and can be used if populations are very high (>500/leaf), but lower numbers are valuable as prey for predator mites. Kelthane is quite effective, as is Agri-Mek.
PRESS RELEASE: CORNELL CENTENNIAL FRUIT FIELD DAYS AT GENEVA
Cornell University will host the Centennial Fruit Field Days and Equipment Show at the New York State Agricultural Experiment Station in Geneva, NY on July 27 and 28 from 8:00 am - 4:00 pm. Fruit growers, consultants, and industry personnel are invited to tour field plots and learn about the latest research and extension efforts being carried out by researchers on the Geneva and Ithaca campuses. The focus will be on all commodities key to New York's $300 million fruit industry: apples, grapes, raspberries, strawberries, peaches, pears, cherries, and nectarines.
"The event celebrates a century of fruit breeding and technology innovation at Cornell's College of Agriculture and Life Sciences, which this year is celebrating its 100th year as the New York State College of Agriculture," said Terence Robinson, associate professor of horticultural sciences and one of the organizers. "On July 27, we will focus on tree fruit technologies and demonstrations and July 28, we will focus on grape and small fruit production."
In addition to the field trials, an international array of equipment will help growers determine which technologies are best for orchard or vineyard. Representatives from various companies will advise growers on the latest technologies. Each day, the Cornell pesticide application technology team will demonstrate different methods of improving deposition and testing sprayers, including tips about nozzle orientation.
The event will be held on the Station's Fruit and Vegetable Research Farm South, 1097 County Road No. 4, 1 mile west of Pre-Emption Rd. in Geneva, NY. Signs will be posted. Attendees will be able to select from tours of apples, stone fruits, small fruits, and grapes. Admission is free and lunch is provided, courtesy of industry sponsors. Pre-registration is encouraged.
The last Fruit Field Day was held in Geneva in 2000 and brought in 425 representatives from nurseries, the New York State Department of Agriculture and Markets, the United States Department of Agriculture, Cornell Cooperative Extension, fruit processors, as well as growers from Western New York, the Hudson Valley, Central New York, the Finger Lakes, Ontario, and neighboring states. Organizers this year expect over 500 attendees. The event is co-sponsored by the New York State Agricultural Experiment Station and the New York State Horticultural Society. For sponsorship and exhibitor information, contact Alison DeMarree at 315-589-9698 or Emailto: AMD15@cornell.edu. More information will be posted as it becomes available. To pre-register, contact Nancy Long at 315-787-2288 or Emailto: NPL1@cornell.edu. More information about this event and a complete agenda for both days is available at: http://www.nysaes.cornell.edu/pubs/press/2004/040622FruitFieldDays.html