Scaffolds
Insects | Credits
SCAFFOLDS Fruit Journal, Geneva, NY                Volume 4
Update on Pest Management and Crop Development      6,26, 1995

COMING EVENTS

                                                     43F       50F
Current DD accumulations (Geneva 1/1-6/26):         1276       875
                       (Highland 3/1-6/26):         1385       864

Coming Events: Ranges:

Spotted tentiform leafminer 2nd flight begins 795-1379 449-880 San Jose scale 1st gen crawlers present 987-1247 569-784 Obliquebanded leafroller summer larvae hatch 1076-1513 630-980 Lesser peachtree borer flight peak 1099-2330 667-1526 Codling moth 1st flight subsides 1112-2118 673-1395 Redbanded leafroller 2nd flight begins 1198-2029 804-1381 American plum borer 1st flight subsides 1217-1659 850-1098 Comstock mealybug 1st adult catch 1270-1673 756-1105 Obliquebanded leafroller 1st flight subsides 1420-2277 899-1546 Apple maggot 1st oviposition 1566-1724 1001-1232

TRAP CATCHES (Number/trap/day)

Geneva:

6/12 6/16 6/19 6/22 6/26 Spotted Tentiform Leafminer 7.1 4.3 12.2 15.3 49.3 Oriental Fruit Moth (apple) 0.5 0.5 0 0.7 8.1 Lesser Appleworm 0.3 0.4 0 0.7 6.3 Codling Moth 6.5 4.4 5.3 2.2 1.1 San Jose Scale 0 0 0 0.2 0 American Plum Borer (cherry) 0.3 0.3 1.2 0.2 0.1 Lesser Peachtree Borer (peach) 6.0 1.9 - 5.1 1.6 Lesser Peachtree Borer (cherry) 3.4 0.8 4.2 3.3 3.1 Peachtree Borer 4.4 3.6 - 5.1 2.5 Obliquebanded Leafroller 0.1* 0.1 3.3 3.0 1.1 Pandemis Leafroller 2.0 1.4 0.8 1.0 0 Apple Maggot 0 0 0 0 0.3*

Highland (Dick Straub, Peter Jentsch)

5/29 6/5 6/12 6/19 6/26 Spotted Tentiform Leafminer 0.5 0.9 2.9 9.1 9.2 Oriental Fruit Moth 0.5 1.1 1.4 0 0.4 Fruittree Leafroller 0 0 0.3 0 0.2 Codling Moth 4.6 4.9 3.5 1.1 8.6 Lesser Appleworm <0.1 0 0 0 0 Sparganothis Fruitworm 0 0.1* 1.1 3.0 2.4 Tufted Apple Budmoth 1.1 1.4 1.0 1.6 1.3 Variegated Leafroller 0 0 0.5* 0.6 4.9 Obliquebanded Leafroller 0 0 0.8* 1.6 5.9 * = 1st catch

PEST FOCUS

Geneva:

Obliquebanded Leafroller DD (base 43) since 1st catch (on 6/12) = 366.

Spotted Tentiform Leafminer DD (base 43) since 1st catch (on 6/19) = 258.

Oriental Fruit Moth and Lesser Appleworm 2nd flights have begun. Apple Maggot 1st catch (on 6/26).

Highland:

Obliquebanded Leafroller catch at peak. DD (base 43) since 1st catch = 384.

Spotted Tentiform Leafminer 2nd flight began, 6/12. DD (base 43) since 1st catch = 384; 2nd generation sap-feeding mines observed.

PROGRESSION OF EVENTS

By:Dave Kain, Entomology, Geneva

LITTLE GREEN GUYS

by:Harvey Reissig & Art Agnello, Entomology, Geneva)
One class of insect pest that seems to be thriving under this year's hot and dry conditions is the green aphid complex, made up of apple aphid, Aphis pomi, and 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. Large numbers of both species may build up on growing terminals on apple trees during summer, particularly when there is an abundance of succulent new foliage. Despite our dearth of rainfall so far this season, there have been several reports of high populations here and there. Both species are apparently common during the summer in New York 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 the season starting in mid-June. Inspect 10 rapidly growing terminals from each of 5 trees throughout the orchard, and record the percentage of infested terminals. No formal studies have been done to develop an economic threshold for aphids in New York orchards, but treatment is recommended if 30% of the terminals are infested with either species of aphid. The larvae of syrphid and cecidomyiid flies 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. Both aphid species are resistant to most organophosphates, but materials in other chemical classes control these pests effectively. Some options for aphid control are Provado, Lorsban, Thiodan, or (more destructive to predator mites) Cygon, Lannate or Vydate.

COMSTOCK MEALYBUG

By:Art Agnello & Dave Kain, Entomology, Geneva
The first adult males of the season should be appearing in pheromone traps any day now, and it shouldn't be long before we start seeing some adult females in pear foliage, followed by their invasive crawler offspring. According to our tests over the past few years, this is the most susceptible stage for chemical control, which we expect sometime during the next couple of weeks, especially in the Hudson Valley.

The following information is taken from the Comstock Mealybug IPM Fact Sheet, No. 22:

The Comstock mealybug (CMB) was first reported in the United States in 1918 concurrently in New York and California, and has since spread to all coastal states and the Ohio and Mississippi River valleys. Its fruit hosts include pear, apple, and peach, and it is also a pest of several ornamental plants such as catalpa, mulberry, pine and others. CMB was first recognized as a fruit pest in the 1930's. From 1950 to 1980, it was infrequently noticed as a fruit pest, but in the early 1980's it caused damage to apple crops in the Hudson and Champlain valleys, and to pears in western New York later in the eighties.

The Comstock mealybug adult female is wingless and elongate-oval in shape, with a many-segmented body (2.5 to 5.5 mm long) and well-developed legs. It has 17 pairs of body filaments, with the caudal (posterior) pair being one-third as long as the body. The legs and antennae are inconspicuous. The body of the adult female is reddish-brown, but has a white appearance because it is covered with wax.

Because of its small size and short life span, the adult male is very unlikely to be seen in the field unless it is captured in pheromone traps; even then it is difficult to distinguish without the aid of a microscope. It has a gnat-like appearance, with delicate, almost veinless wings, a light reddish-brown body (about 1 mm long), and two caudal filaments as long as or longer than the body. It is peculiar in having three pairs of eyes (dorsal, lateral, and ventral). The legs and 10-segmented antennae are apparent, but the mouthparts are absent.

There are two generations of Comstock mealybug in New York, each taking 60 to 90 days to complete, depending on seasonal temperatures. The egg is generally thought to be the primary overwintering stage, but recent evidence from western N.Y. indicates that some nymphs and adult females from the second (summer) generation overwinter, with eggs being laid in the spring rather than the previous fall. Adult females and males emerge at the same time, from late June to mid-July for the first (overwintering) generation, and late August to mid-September for the second (summer) generation. Adult females are present for a total of 4-6 weeks, and oviposit for about one week after mating. Males survive for only a few days after emerging.

The eggs are elliptical (0.3 mm long and 0.17 mm wide) and bright orange-yellow, but may appear duller because of the waxy filaments covering them. Eggs are laid in jumbled masses along with the waxy filamentous secretions in protected places such as under bark crevices, near pruning cuts, and occasionally in the calyx of fruit. The summer-generation eggs are laid from mid-June through late July, and the overwintering eggs from mid-August into October. The summer generation eggs have an incubation period of about 11 days.

The first and second larval instars of the female and male CMB are virtually indistinguishable. They appear similar to adult females except that they are smaller, more oval-shaped, lack the long body filaments, and are more orange-yellowish because they have less wax covering. The first instar female crawler is flattened (0.3 to 0.5 mm long) and pale yellow, becoming darker in time. The second (0.9 to 1.2 mm long) and third (1.7 to 2.5 mm long) instar females are similar in appearance, but become progressively browner and redder.

The third instar of the immature male, called a "pro-pupa", is contained in a cocoon that begins forming toward the end of the second instar. It is 0.9 to 1.2 mm long and elongate-oval, with the head, thorax, and abdomen fused. The fourth stage of the immature male is the pupa. It is elongate, 1.2 to 1.4 mm long, and light reddish-brown. As with the adult male, it has three pairs of eyes and 10-segmented antennae.

The overwintered eggs hatch from mid-April through May and the nymphs (crawlers) migrate from the oviposition sites to their feeding sites on terminal growth and leaf undersides of trees and shrubs. This hatch is completed by the petal fall stage of pears. Nymphs that hatch from these overwintered eggs are active from roughly early May to early July. As the nymphs approach the adult stage, they tend to congregate on older branches at a pruning scar, a node, or at a branch base, as well as inside the calyx of pears. Second- (summer) generation nymphs are present from about mid-July to mid-September.

The Comstock mealybug poses two major concerns for the pear processing industry of New York: First, the emergence of crawlers and adult females from the calyx of pears at the packinghouse creates a nuisance to workers. Second, pears to be made into puree typically are not peeled or cored by New York processors, so infestations can potentially result in unacceptable contamination of the product.

Another problem, of concern to apple growers in the 1930s and 1940s, and again in the Hudson and Champlain Valleys in the early 1980s, is that the honeydew secreted by the crawlers is a substrate for sooty molds growing on the fruit surface. This problem also occurs on peaches in Ontario, Canada. These molds result in a downgrading of the fruit, and are therefore an additional cause of economic loss.

To date, the Comstock mealybug has been a problem to growers of processing pears because of the contamination and aesthetic reasons noted. Crawler infestation of pears destined for processing can be determined by examination of the calyx end. Cut the pear lengthwise to expose the inner calyx area, which is often concealed in the whole fruit. Once the insects have reached these sites, it is nearly impossible to remove them. Such an infestation generally indicates the need for one or more insecticide sprays during the growing season, directed against the migrating crawlers.

Examine the terminal growth for crawler activity periodically throughout the summer. Crawler and adult female activity can also be monitored by wrapping black electrical or white carpet tape around low scaffold branches and inspecting for crawlers that have been caught by the tape. They can be recognized with a hand lens or, with some experience, by the unaided eye.

Watch this space for our best advice on when to apply a material such as Penncap-M, Diazinon, Lannate, or (on apples only) Lorsban to control this insect.


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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