Volume 6, No. 15 June 30, 1997
43F 50F
Current DD accumulations (Geneva 1/1-6/30): 1206 739
(Highland 1/1-6/30): 1395 853
Coming Events: Ranges:
Comstock mealybug 1st adult catch 1270-1673 756-1105
Oriental fruit moth 2nd flight begins 1152-1819 772-1215
Spotted tentiform leafminer 2nd flight peak 1295-2005 824-1355
Lesser appleworm 2nd flight begins 1152-2302 778-1531
American plum borer 1st flight subsides 848-1668 440-1205
Obliquebanded leafroller eggs hatch 1076-1513 630-980
Apple maggot 1st catch 1045-1671 629-1078
Codling moth 1st flight subsides 1112-2118 673-1395
Redbanded leafroller 2nd flight begins 1198-2029 804-1381
PEST FOCUS
Geneva: Spotted tentiform leafminer 2nd flight began 6/23. DD(base 43F) = 230.
Highland: Spotted tentiform leafminer 2nd flight began 6/16. DD(base 43F) = 332.
TRAP CATCHES (Number/trap/day)
Geneva:
6/16 6/19 6/23 6/26 6/30
Redbanded Leafroller 0 0 0 0.2 0
Spotted Tentiform Leafminer 8 6 28 175 406
Lesser Appleworm 1.4 2.0 0.4 0 0
Oriental Fruit Moth (apple) 1.0 1.2 0.4 0.2 0.1
Oriental Fruit Moth (peach) 0.1 0 0 0 0
San Jose Scale 0.1 0.3 0.4 0 0
Codling Moth 6.0 5.2 2.5 1.2 0.8
American Plum Borer 2.4 1.2 1.1 1.0 0.6
Lesser Peachtree Borer 3.4 0.8 2.6 2.0 1.6
Peachtree Borer 2.0 1.2 3.9 8.5 2.0
Pandemis Leafroller 0.8* 0.7 1.4 0.3 0.5
Obliquebanded Leafroller 0 0.5* 3.3 2.7 0.6
Apple maggot 0 0 0 0 0
Highland (Dick Straub, Peter Jentsch):
6/2 6/9 6/16 6/23 6/27
Redbanded Leafroller 0.4 0.1 0 0 0.9
Spotted Tentiform Leafminer 5.6 0.1 7.4 74.0 39.4
Oriental Fruit Moth 1.1 1.2 1.4 0.3 0.9
Lesser Appleworm 1.3 1.6 1.3 0.4 2.0
Codling Moth 1.6 1.7 1.6 5.6 2.6
Fruittree Leafroller 0 0 0 0 0
Tufted Apple Budmoth 0 2.9* 2.0 1.3 2.9
Obliquebanded Leafroller 0 0.2* 1.8 0.9 0.3
Sparganothis Fruitworm 0 0.1* 0 1.3 1.4
* = 1st catch
by Art Agnello & Dave Kain
Entomology, Geneva
The first adult males of the season should begin to appear soon in pheromone traps, so it shouldn't be long before we start seeing some adult females in pear foliage, followed by their invasive crawler offspring. We realize that the Bartlett fruit set is down considerably this season, but for those who do have a crop and don't want it threatened by mealybug infestations, the crawlers are 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: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 some nymphs and adult females from the second (summer) generation may also 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 elongate, orange-yellow eggs are laid in jumbled masses along with 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 early larval instars of the CMB are similar to adult females (wingless and elongate-oval in shape, with a many-segmented body) except that they are smaller, more oval-shaped, lack the long body filaments, and are orange-yellowish because they have less wax covering. Later instars are similar in appearance, but become progressively browner and redder.
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. An infestation generally requires 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.
Sometime in early August, when we detect crawlers in some problem blocks we are monitoring, we'll advise an application of a material such as Penncap-M, Provado, Diazinon, Lannate, or (on apples only) Lorsban to control this insect.
MIND THE BARK
Dogwood borers should be laying eggs in susceptible apple orchards now (those with succulent burrknot tissue or suckers). The larva of this clearwing moth feeds on apple trees, primarily on burrknot tisse on clonal rootstocks. Burrknots are aggregations of root initials that can develop on the above-ground portion of the rootstock; all commercial dwarfing and semi-dwarfing rootstocks have a tendency to develop burrknots. Some chemicals with hormone effects, such as NAA, can increase the expression of burrknots, as will failure to keep the area around the trunk weed-free and open to sunlight. White latex paint brushed on the exposed portion of the rootstock will prevent new infestations of the borers, and also protect against southwest injury to the bark. Dilute trunk applications of an insecticide with good residual activity can provide control of established infestations. At this point in the season, a spray of Lorsban 50WP or Thiodan 50WP would be the most effective materials if applied anytime until Aug. 15, bearing in mind the specific pre-harvest intervals.
MODEL STATUS
The typical summer temperatures of the last week have moved some of the earliest OBLR sites into the 360+ DD window that we estimate to be the time of first hatch (in western N.Y.; this occurred over a week ago in the Hudson Valley). Growers electing a Confirm program for OBLR control this year should definitely have their first application on by this point. Those waiting for a scouting decision to apply a treatment have until the DD total reaches 600 (base 43 F) for the recommended sampling time. The OBLR DD totals we've calculated as of this morning, 6/30, are given below; note that the peak hatch rate (25% of total) is predicted at 450 DD; 50% hatch comes at 630 DD, and 720 DD marks the median development point of the earliest emerging larvae:
SITE FIRST CATCH DD TOTAL Highland June 9 Knowlesville June 16 (Waterport) Geneva June 17 Wolcott June 19 (Sodus)
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:
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Photographs courtesy of New York State Integrated Pest Management Program