Scaffolds Fruit Journal, Cornell University NYSAES

Insects| Chemical News | Credits

Volume 6, No. 19				  July 28, 1997


                                                      43F       50F
Current DD accumulations (Geneva 1/1-7/28):         1934      1271
                       (Highland 1/1-7/28):         2296      1537

Coming Events:                              Ranges:
Peachtree borer flight peaks                    864-2241  506-1494
American plum borer 2nd flight peaks           1648-2612 1037-1840
STLM 2nd flight subsides                       1773-2514 1148-1818
Oriental fruit moth 2nd flight subsides        1806-2783 1164-1963
Apple maggot flight peaks                      2033-2688 1387-1804
San Jose scale 2nd flight peaks                2136-2591 1479-1874

   Highland: Spotted Tentiform Leafminer tissue feeders present; numbers 
             Codling moth 1st flight began 5/19.  DD (50 F) since then =
     Geneva: Spotted Tentiform Leafminer 2nd flight began 6/23; DD (43 
             F) = 958.
             American Plum Borer 2nd flight began 7/25.
             San Jose Scale 2nd flight began 7/28.
             Codling moth 1st flight began 5/19.  DD (50 F) since then =

TRAP CATCHES (Number/trap/day)
                                  7/14   7/17   7/21   7/24   7/28
Redbanded Leafroller               5.6    4.0    3.0    1.1    0.7
Spotted Tentiform Leafminer        470    732    976    800    665
Lesser Appleworm                   1.0    1.2    1.4    1.3    0.5
Oriental Fruit Moth (apple)        3.0    2.5    2.0    2.5    2.3
Oriental Fruit Moth (peach)          0      0      0      0      0
San Jose Scale                     0.1      0    0.3    0.1   23.2
Codling Moth                       0.3    4.2    4.5    2.9    2.3
American Plum Borer                0.1    0.2    0.8    1.5    1.7
Lesser Peachtree Borer             2.0    5.0    2.9    0.8    0.7
Peachtree Borer                    0.6    0.5    0.1    5.8    7.7
Pandemis Leafroller                  0      0      0      0      0
Obliquebanded Leafroller             0    0.2      0      0      0
Apple maggot                      0.06   0.08    0.1      0    0.3

Highland (Dick Straub, Peter Jentsch):
                                  6/27    7/7   7/14   7/21   7/28
Redbanded Leafroller               0.9    5.1    9.1    2.3    2.4
Spotted Tentiform Leafminer       39.4   85.3   59.7   46.0   28.4
Oriental Fruit Moth                0.9    1.3    1.3    0.3    0.6
Lesser Appleworm                   2.0    0.2    0.4    0.9    1.2
Codling Moth                       2.6    1.9    0.6    1.2    1.0
Fruittree Leafroller                 0      0      0      0      0
Tufted Apple Budmoth               2.9    1.3    0.4      0    0.4
Obliquebanded Leafroller           0.3    0.6    0.2    0.1    0.1
Sparganothis Fruitworm             1.4    3.9    0.7    0.1    0.3
Apple Maggot                         0      0    0.1*   0.9    1.1
Variegated Leafroller                -      -      0    0.4*   0.2
                                       * = 1st catch


And Maggots Have Eaten Them, But Not For Love

by Harvey Reissig & Art Agnello
Entomology, Geneva

Even though apple maggot flight is not particularly strong in most N.Y. orchards 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 begin to 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 generally require protection only from about mid-July through 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.

Apple maggot adult

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.

Fruit deformations caused by severe apple maggot oviposition damage

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 1997 Pest Management Recommendations for Commercial Tree-Fruit Production (p. 84), 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 7/7.) 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 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 few 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 of these studies can be summarized as follows:

  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.


by Dave Kain & Art Agnello
Entomology, Geneva

Things are a little slow this week so we thought we'd catch you up on our comparison of events so far this year with last season and the "normal":

DD (base 43°F)
                               Normal     1996     1997
DD43 to date (7/28)            2096       1998     1934
PPS 1st oviposition              82         48      124
GFW flight peak                 137        206      234
ERM egg hatch begins            284          -      266
RBLR 1st flight peak            305        379      234
STLM 1st flight peak            330        379      360
OFM 1st flight peak             423        379      464
CM 1st catch                    487        505      426
LPTB 1st catch                  588        602      464
APB 1st flight peak             701        625      733
SJS 1st flight peak             674          -      646
OBLR 1st catch                  922        962      847
PTB 1st catch                  1084        851      646
STLM 2nd flight begins         1068       1034     1005
OBLR 1st flight peak           1164       1034     1005
AM 1st catch                   1350       1481     1384
APB 2nd flight begins          1616       1748     1760
CM 2nd flight begins           1881       1847     1654
CMB 1st adult catch            1440       1396     1402
LAW 2nd flight begins          1630       1748     1442
OFM 2nd flight begins          1436       1481     1296
RBLR 2nd flight begins         1503       1305     1296
SJS 2nd flight begins          1696       1748     1934
STLM 2nd flight peak           1642       1748     1760




We have just been informed of the approval of Pyramite's 24(c) label for apples. One application is allowed against mites this season, and a copy of the label (available from distributor) must be in the applicator's possession.

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