Scaffolds

Insects | Credits


SCAFFOLDS Fruit Journal, Geneva, NY                             Volume 5 
Update on Pest Management and Crop Development                 July 22, 1996

COMING EVENTS

43F 50F Current DD accumulations (Geneva 1/1-7/22): 1847 1231 (Highland 1/1-7/22): 2266 1186 Coming Events: Ranges: American plum borer 2nd flight peaks 1649-2612 1407-1840 Oriental fruit moth 2nd flight peaks 1000-2908 577-2066 Obliquebanded leafroller 1st flight subsides 1420-2277 899-1546 Redbanded leafroller 2nd flight peaks 1479-2443 952-1698 STLM 2nd generation tissue feeders present 1504-2086 952-1201 Apple maggot 1st oviposition punctures 1566-2200 1001-1575 TRAP CATCHES (Number/trap/day) Geneva: 7/5 7/8 7/11 7/15 7/18 7/22 Redbanded Leafroller 0 0.3 0.2 0.5 0 0.4 Spotted Tentiform Leafminer 378 568 511 423 709 316 Oriental Fruit Moth 0.1 1.7 4.8 6.5 8.2 5.3 Lesser Appleworm 0 0.3 0.2 0.5 1.3 2.5 Codling Moth 10.6 6.7 1.7 2.6 1.0 3.1 San Jose Scale 0 0 0 0 0.5 0.1 American Plum Borer 0.1 0.5 0.2 0.4 1.5 2.4 Lesser Peachtree Borer (cherry) 0.6 0 0.2 0 0 0 Lesser Peachtree Borer (peach) 1.6 0.7 0.7 0.4 1.3 1.0 Peachtree Borer 4.9 5.2 2.5 0 5.2 1.4 Pandemis Leafroller 0.3 0.2 0.2 0 0 0 Obliquebanded Leafroller 0.1 1.0 0.3 0 0 0.3 Apple Maggot 0 0.2* 0 0.1 0.1 0 Highland (Dick Straub, Peter Jentsch) 6/17 6/24 7/1 7/8 7/15 7/22 Redbanded Leafroller 0 0.8 1.8 3.0 3.8 0.1 Spotted Tentiform Leafminer 55.1 24.4 1.7 33.9 38.3 27.9 Oriental Fruit Moth 0 0.6 0.4 0.9 0.5 0.9 Lesser Appleworm 0.9 0.9 0 0.2 0.1 0.4 Codling Moth 5.2 2.9 1.8 1.4 0.2 1.4 Fruittree Leafroller 0 0.1* 0 0 0 0 Tufted Apple Budmoth 0.8 1.6 1.0 1.1 0.9 0.4 Obliquebanded Leafroller 4.9 1.8 2.4 2.6 0.4 0.2 Sparganothis Fruitworm 0.5 2.0 1.8 0.9 0.3 0 Apple Maggot - 0 0.2* 0.3 0.3 0.8 Variegated Leafroller - - - 0 0.1* 0.1 * = 1st catch Pest Focus Geneva - DD (base 43 F) since 1st catch of Obliquebanded Leafroller (6/17 in Geneva) = 885 Spotted Tentiform Leafminer 2nd flight started 6/20; DD(base 43 F) = 813 Lesser appleworm and San Jose scale 2nd flights began today.



CONFIRM AND OBLR: QUESTIONS AND COMMENTS

By: Harvey Reissig and Art Agnello, Entomology, Geneva

During the last 2 weeks, many growers and fieldmen both in NY state and from other states plagued with leafroller problems have called us with questions and comments about the relatively large numbers of live OBLR larvae observed in growing terminals in plots that have been treated with Confirm. Some growers have even become so concerned about the presence of these larvae that they have applied treatments of conventional materials to plots previously sprayed with Confirm.

We have set up experimental plots in two orchards in western NY to compare different schedules of Confirm starting at first moth catch and later timings with a standard 3-spray program of Lorsban starting at first hatch. To date, our observations of larvae in the growing terminals in the various treatments of Confirm are very similar to the reports we have received from growers. There are a lot of larvae in terminals in all of the plots treated with Confirm, even in the 3-spray program in which the first spray was applied about June 17, followed by two additional sprays at 14-day intervals. These larvae in terminals in the Confirm plots appear to be quite healthy, and feeding normally, and probably have not yet been ingested much, if any, Confirm because this expanding new foliage on these terminals has very little foliar residues of this material.

However, a casual examination of the fruit in the various plots revealed that the effectiveness of fruit protection in the various plots treated with Confirm was similar to that in plots treated with the Lorsban standard sprays. Although we realize that it is still relatively early in the season to estimate fruit damage from this summer generation of OBLR larvae, these initial observations in our plots support our previous conclusions that Confirm should still protect fruit just as well as any other available standard materials. Probably, the live larvae in the growing terminals in Confirm plots should not be viewed with alarm because it is likely that if they move off of these terminals to feed on older foliage or fruit, they will eventually ingest a sufficient dosage of Confirm to kill them outright or cause them to cease feeding before they inflict a large amount of fruit damage. Therefore, we would suggest that if you want to monitor the effectiveness of Confirm for OBLR control during the next several weeks, that you examine fruit for damage rather than monitoring populations of live larvae in the terminals.

APPLE MAGGOT

By: Harvey Reissig & Art Agnello, Entomology, Geneva

Even though the current apple maggot flight is not particularly strong yet in most N.Y. orchards, 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 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 1996 Pest Management Recommendations for Commercial Tree-Fruit Production (p. 82), 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 7/8.) 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.

CODLING MOTH MODEL

By: Harvey Reissig & Art Agnello, Entomology, Geneva

Codling moth (CM) overwinters as a larva in a cocoon under loose bark on the tree trunk. Adults emerge during bloom, and the first flight continues until about 30 days past petal fall. Eggs, laid singly on the upper surface of leaves or fruit, start to hatch at petal fall and continue for two to three weeks. Larvae feed only on fruit. Surface bites, referred to as stings, cause blemishes; deeper injuries are caused by feeding inside the fruit. Fruits injured by extensive internal feeding usually drop in the middle of June, at which time early-season damage becomes noticeable. Adults from the second or summer generation of CM start to fly about mid-July, and the peak flight in western New York occurs around the first week in August. Larvae from this generation are active in fruit throughout August. Fruit damage by the second generation is generally more serious than that of the first.

Adult males can be captured in pheromone traps, but numbers of males captured in these traps cannot be related to potential fruit damage. Thus, pheromone traps are used only to monitor the seasonal activity patterns of adults within an area. Developmental models, based on temperature accumulations after the first catch of males, can be used to predict the first egg hatch of CM; this approach is commonly used to time initial control sprays for CM in the western United States. It is not practical to monitor commercial apple orchards for CM eggs or larval fruit entries because of the theoretical zero tolerance for internal fruit damage.

The codling moth is attacked by both parasites and predators, but these natural enemies cannot effectively control this pest in commercial orchards. To kill the larvae before they enter the fruit, chemical sprays for CM must be initiated before eggs hatch. In New York, the first generation of CM is normally controlled by sprays for plum curculio at petal fall, so special sprays are not necessary. CM is most effectively controlled by the same conventional insecticides used against the plum curculio (organophosphates and synthetic pyrethroids). CM can also be controlled by biorational pesticides such as bacteria(Bacillus thuringiensis), insect growth regulators, viruses, and botanicals, although many of these products are less effective than standard insecticides. In New York, the second generation of CM is normally controlled by the same conventional insecticides used on apple maggot so no special sprays are required in most commercial orchards. However, in cases where summer organophosphate sprays have been withheld for more than one season because of low apple maggot pressure, there is a danger that CM will re-establish itself as a primary cause of fruit damage. In these cases, growers should apply preventive pesticide sprays according to the developmental model.

The model for 2nd generation codling moth larvae predicts that a control spray should be applied in problem orchards 1260 DD (base 50 F) after the start of the FIRST flight (5/28 in Geneva, 5/20 in the Hudson Valley). As of today, 7/22, 958 DD have accumulated in Geneva and 1186 at Highland. Keep your eye on the thermometer so that you will be timely with any OP applications you should decide to make.

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.



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
Department of Entomology, NYSAES
Geneva, NY 14456-0462
Phone: 315-787-2341 FAX:315-787-2326
E-mail: art_agnello@cornell.edu


Back to the Scaffolds 1996 Directory
Scaffolds 1995 Directory