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SCAFFOLDS Fruit Journal, Geneva, NY			Volume 4 
Update on Pest Management and Crop Development		July 24, 1995 

COMING EVENTS

                                                      43F       50F
Current DD accumulations (Geneva 1/1-7/24):         2073      1476
                       (Highland 3/1-7/24):         2199      1490

Coming Events:                              Ranges:
Peachtree borer flight peak                     869-2241    506-1494
Lesser peachtree borer flight peak             1099-2330    667-1526
Obliquebanded leafroller 1st flight subsides   1420-2277    899-1546
Redbanded leafroller 2nd flight peak           1479-2443    952-1698
Codling moth 2nd flight peak                   1587-3103   1061-2212
STLM 2nd flight subsides                       1773-2484   1148-1740
American plum borer 2nd flight peak            1975-2612   1407-1840
Apple maggot flight peak                       2033-2688   1387-1778
Comstock mealybug 2nd gen crawlers emerging    2106-2768   1447-1924
San Jose scale 2nd flight peak                 2136-2533   1567-1818


TRAP CATCHES (Number/trap/day)
Geneva:   
                                  7/10   7/13   7/17   7/20   7/24
Redbanded Leafroller               0.1    0.2    0.3    0.4    0.2
Spotted Tentiform Leafminer        261    405    599    291    161
Oriental Fruit Moth (apple)        3.4    1.8    1.9    1.1    0.5
Lesser Appleworm                   6.1    2.2    0.9    1.8    0.7
Codling Moth                       3.5    0.8    2.9    2.1    7.7
San Jose Scale                     0.3    0.3    9.0    5.1    5.8
American Plum Borer (cherry)       1.5    2.0    1.9    3.0    3.1
Lesser Peachtree Borer (peach)     1.1    3.3    2.9    1.5    3.3
Lesser Peachtree Borer (cherry)    1.5    3.2    3.4    1.5    1.2
Peachtree Borer                    0.8    2.5    1.9    2.0    1.5
Obliquebanded Leafroller             0      0    0.1      0      0
Pandemis Leafroller                  0      0      0      0      0
Apple Maggot                         0    0.2    1.1    0.5    1.4

Highland (Dick Straub, Peter Jentsch)
                                  6/26    7/3   7/10   7/17   7/24
Redbanded Leafroller                 0      0    1.6    1.6    0.6
Spotted Tentiform Leafminer        9.2    2.6   24.9   35.9   20.8
Oriental Fruit Moth                0.4    0.6    1.4    0.9    1.1
Fruittree Leafroller               0.2    0.3      0    0.1      0
Codling Moth                       8.6    0.8    0.4    0.6    1.1
Lesser Appleworm                     0      0      0      0    0.6
Sparganothis Fruitworm             2.4    3.8    1.1    0.6      0
Tufted Apple Budmoth               1.3    2.8    0.1    0.4      0
Variegated Leafroller              4.9      -      0    0.1    0.1
Obliquebanded Leafroller           5.9    7.2    0.9    0.1    0.2
Apple Maggot                         -      0      0      0    0.2*

                                                        * = 1st catch

PEST FOCUS
Geneva: 
   Apple Maggot catch increasing.
   Codling Moth 2nd flight beginning.
Highland: 
   Apple Maggot 1st catch 7/20.
     

MID-SUMMER INSECT REVIEW

By:(Harvey Reissig, Entomology, Geneva)

APPLE MAGGOT

Even though the current apple maggot flight is not particularly strong yet in most N.Y. orchards, probably because it's been so dry this season, we are entering the traditional period of peak emergence. Following is some general information on the biology and life history of this well-known insect.

The apple maggot overwinters as a pupa in the soil. Adults from the single generation of flies emerge in late June to early July. Females cannot lay eggs until they become reproductively mature, 7-10 days after emergence. Females lay eggs in fruit and larvae develop there, emerging in the autumn after the fruit has fallen and entering the soil to pupate. Flies are active from July to mid-September, but commercial orchards require protection only from about mid-July to mid-August. Flies do not reach orchards in large numbers until mid-July, and before this date fruit remaining on the tree is unfavorable for larval development, so early infestations do not cause sustainable populations in the orchard. In addition, for unknown reasons, fly activity between about August 20 and September 15 does not usually cause serious damage in commercial orchards in New York.

Larval tunneling inside the fruit causes it to become rotten and unmarketable. Early stings caused by punctures from the female's ovipositor may severely deform the fruit of some varieties, even though no larvae survive.

Monitoring to determine whether control sprays are necessary is recommended primarily in orchards that are not near large sources of outside infestation (such as abandoned orchards), and those with no indigenous infestations of flies. Theoretically, there is absolutely no tolerance for AM damage in fruit. In practice, AM damage is not usually detected in normal fruit inspections unless there is approximately 5 percent fruit damage.

Small wasps parasitize AM larvae in fruit, and predators such as birds and crickets may eat larvae or pupae in or near the soil. In natural, unsprayed apple and hawthorn trees, AM populations are not regulated by natural enemies. Parasites and predators are also ineffective at controlling AM in commercial orchards.

AM flies have a limited migratory capability, so all apple and hawthorn trees within 1/4-1/2 mile of commercial orchards should be removed if possible. Do not allow dropped fruit to remain beneath the tree for more than one to two days. Eliminating fruit drops will break the life cycle of flies in an orchard by preventing larvae from exiting the fruit and entering the soil.

AM flies can be trapped out in small, well-pruned trees that are not near large sources of outside infestations. A relatively high density of sticky red spheres (plain or volatile-baited) is required, approximately 1 trap per 100 apples. Mass trapping is usually less effective than chemical control, and AM may still damage 1-5% of fruit from mass-trapped orchards.

Most commercial orchards have no indigenous populations of flies. Therefore, chemical control sprays are usually directed against flies immigrating into orchards from outside, unsprayed hosts, including both apples and hawthorns. Most insecticides, particularly organophosphates, are remarkably effective in controlling adults. Insecticides must kill females before they oviposit in the fruit. Residual effectiveness of insecticides is particularly important in controlling AM in commercial orchards when flies are continuously immigrating.

Insecticides can be applied according to trap catches as described in the 1995 Pest Management Recommendations for Commercial Tree-Fruit Production (p. 96), or on a standard or modified IPM schedule. The standard schedule requires an initial spray 7-10 days after the first emergence of flies, followed by additional sprays at 10-14-day intervals until August 15-20. (The first AM fly in Geneva was trapped on 6/26.) The modified IPM schedule requires only three sprays, on approximately July 15, August 1, and August 15. We would suggest that growers in high maggot-pressure areas maintain a standard spray schedule, or at least be vigilant in checking traps twice a week, in order not to be caught unprotected during this peak flight period.

A few words may be in order here about the continuing research on when to terminate sprays for apple maggot in late summer. Most people are aware that each year in N.Y. orchards, substantial numbers of AM flies are captured on monitoring traps late in the season, and growers are naturally concerned about potential fruit infestation from these late season survivors. For the past two years, we have conducted trials in a heavily infested research orchard of McIntosh and Cortland trees by applying bi-weekly applications of Guthion beginning in early July and continuing for 2, 3, 4, and 5 total sprays. New oviposition punctures were checked weekly on "scout" apples clipped to the trees, and female AM flies captured throughout the flight period were dissected to check for the presence of eggs. The results both years were the same: 1) Gravid female flies were present in the orchards in September and October. 2) Although peak oviposition times varied among apple varieties from year to year, only trace amounts of oviposition occurred in September. 3) AM fruit damage in the unsprayed check trees was substantial in both varieties (between 20-45%), with higher damage levels occurring in the Cortland apples. However, 4) There was no statistical difference in fruit damage among any of the treatments regardless of spray termination date, which ranged from August 3 to September 7. We regard these results as corroboration of our long-standing recommendations that a final spray be applied around the middle of August to effectively control apple maggot in most commercial orchards. These studies are being repeated again this season.

WOOLLY APPLE APHID

The woolly apple aphid (WAA), Eriosoma lanigerum, colonizes both aboveground parts of the apple tree and the roots, and commonly overwinters on the roots.In the spring, nymphs crawl up on apple trees from the roots to initiate aerial colonies. Most nymphs are born alive to unmated females on apple trees during the summer. Colonies initially build up on the inside of the canopy on sites such as wounds or pruning scars and later become numerous in the outer portion of the tree canopy, usually during late July to early August.

Aerial colonies occur most frequently on succulent tissue such as the current season's growth, water sprouts, unhealed pruning wounds, or cankers. Heavy infestations cause honeydew and sooty mold on the fruit and galls on the plant parts. Severe root infestations can stunt or kill young trees but usually do not damage mature trees. Large numbers of colonies on trees may leave sooty mold on the fruit, which annoys pickers because red sticky residues from crushed WAA colonies may accumulate on their hands and clothing.

During late May to June, water sprouts, pruning wounds, and scars on the inside of the tree canopy should be examined for WAA nymphs. During mid-July, new growth around the outside of the canopy should be examined for WAA colonies. No economic threshold has been determined for treatment of WAA. Aphelinus mali, a tiny wasp, frequently parasitizes WAA but is very susceptible to insecticides and thus does not provide adequate control in regularly sprayed commercial orchards. Different rootstocks vary in their susceptibility to WAA. The following resistant rootstocks are the only means of controlling underground infestations of WAA on apple roots: MM.106, MM.111, and Robusta. WAA is difficult to control with insecticides because of its waxy outer covering and tendency to form dense colonies that are impenetrable to sprays. WAA is resistant to the commonly used organophosphates, but other insecticides that are effective include Lorsban, Thiodan, and Penncap-M.

CODLING MOTH MODEL

The developmental model for 2nd generation codling moth larvae predicts that a control spray should be applied in problem orchards 1260 DD (base 50F) after the start of the FIRST flight (5/17 in Geneva, 5/15 in the Hudson Valley). As of today, 7/24, 1261 DD have accumulated in Geneva and 1397 at Highland.


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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