Insects | Diseases | Credits
SCAFFOLDS Fruit Journal, Geneva, NY Volume 5 Update on Pest Management and Crop Development June 24, 1996
COMING EVENTS43F 50F Current DD accumulations (Geneva 1/1-6/24): 1134 715 (Highland 1/1-6/24): 1496 952 Coming Events: Ranges: Oriental fruit moth 1st flight subsides 781-1574 442-1026 Lesser appleworm 1st flight subsides 818-1548 444-999 American plum borer 1st flight subsides 848-1659 440-1098 Obliquebanded leafroller 1st flight peak 869-1548 506-987 San Jose scale 1st generation crawlers present 987-1247 569-784 Pear psylla 2nd brood hatch 992-1200 609-763 Apple maggot 1st catch 1045-1662 629-1078 Obliquebanded leafroller summer larvae hatch 1076-1513 630-980 TRAP CATCHES (Number/trap/day) Geneva: 6/6 6/10 6/13 6/17 6/20 6/24 Redbanded Leafroller 0.3 0 0 0 0 0 Spotted Tentiform Leafminer 29.2 15.4 5.3 3.8 22 69 Oriental Fruit Moth 1.8 0.8 0.5 0 0 0 Lesser Appleworm 0.8 0.5 0.7 0 0 0 Codling Moth 5.3 5.5 21.5 2.5 5.8 0.9 San Jose Scale 0.5* 0 0 0.1 0 0 American Plum Borer 1.7 1.8 1.8 3.0 1.5 0.4 Lesser Peachtree Borer (cherry) 0.2 0 0.5 0.8 0 0 Lesser Peachtree Borer (peach) 0.2* 0.8 3.7 3.1 1.2 1.3 Peachtree Borer - 0 11.7* 8.3 3.5 5.4 Pandemis Leafroller - 0 0 0.4* 0.8 0.1 Obliquebanded Leafroller - 0 0 0.8* 1.2 0.3 Apple Maggot - - - - - 0 Highland (Dick Straub, Peter Jentsch) 5/20 5/28 6/3 6/10 6/17 6/24 Redbanded Leafroller 1.0 0.6 0.6 0 0 0.8 Spotted Tentiform Leafminer 4.7 5.1 0.3 1.8 55.1 24.4 Oriental Fruit Moth 1.0 0.9 1.2 1.4 0 0.6 Lesser Appleworm 0.1* 0.2 0.2 0.1 0.9 0.9 Codling Moth 0.1* 2.8 4.1 6.8 5.2 2.9 Fruittree Leafroller 0 0 0 0 0 0.1* Tufted Apple Budmoth 0 0.4 0.8 0.6 0.8 1.6 Obliquebanded Leafroller - - 0 0.1* 4.9 1.8 Sparganothis Fruitworm - - 0 0.1* 0.5J 2.0 Apple Maggot - - - - - 0 * = 1st catch Pest Focus Highland - DD (base 43F) since 1st catch of Obliquebanded Leafroller (6/10 in Highland) = 392. STLM 2nd flight started 6/17; DD (base 43F) = 177. Geneva - DD (base 43F) since 1st catch of Obliquebanded Leafroller (6/17 in Geneva) = 173. STLM 2nd flight started 6/20; DD (base 43F) = 100. Wayne Co. - 1st Comstock Mealybug adult males caught in traps, 6/24.
By: Wayne Wilcox, Plant Pathology, Geneva
This season is shaping up as the best of times (for plant pathogens) and the worst of times (for their hosts). A quick rundown on the current situation:
Brown rot is starting to show up, and recent rains will make it worse. This is particularly true for orchards where brown rot has already gotten established, since the presence of new spores in the tree allows the disease to rapidly "snowball". Ditto for cherry orchards with lots of mummies, since these are excellent sources of inoculum right through harvest, especially when they're wet. For fruits that are still a month or more away from harvest, captan and/or sulfur is/are legal, economical, and should provide adequate protection until closer to harvest. As fruit begin to ripen, they become much more susceptible to brown rot and justify the additional expense of the dicarboximide and sterol inhibitor fungicides, which are more effective.
Dicarboximides (Rovral and Ronilan). These provide both protectant and limited systemic activity. Significantly, they also interfere with the production of brown rot spores from infected tissues, so they are useful in slowing down the spread of an epidemic. The PHI for Rovral has recently increased: it was 0 days, now it's 7 days (unless you have product bearing the old label). Ronilan is restricted to a single preharvest spray with a 14-day PHI, no label for plums or prunes.
Sterol inhibitors (Funginex, Indar, and Orbit). Forget Funginex--it's not even in the same league as Indar and Orbit, both of which are excellent. Orbit is labeled for two preharvest sprays starting 10 to 14 days before harvest with a 0-day PHI. No label for Orbit on cherries or "prunes" (although "plums" are OK). Indar is labeled at 7 to 10 day intervals beginning 2 to 3 weeks before harvest, with a 0-day PHI. No label for Indar on prunes or plums, but cherries are OK. Both materials provide reasonable control of powdery mildews and Indar also picks up cherry leaf spot.
For the last 3 years, Indar has consistently outperformed all other brown rot fungicides in our sour cherry trials at Geneva (Orbit wasn't included in any of these trials). We've always included a surfactant (Latron B-1956) as suggested on the label, but I don't have a good feeling for how necessary this really is.
Other Stone Fruit Diseases
Symptoms of two bacterial diseases are becoming common. These are bacterial canker (gumming cankers and dead bud clusters, shot-holing of leaves, flat or sunken brown lesions on fruit) and bacterial spot (small brown or black fruit spots, most common on apricots, peaches/nectarines, and Japanese plums). Bacterial canker is a difficult disease to control, although some growers (particularly in the Hudson Valley) have had reasonable success with copper sprays in the autumn and spring. However, there's little that can be done for it at this time of year. Mycoshield (terramycin or oxytetracycline) is labeled for control of bacterial SPOT on peaches, with a 3-week PHI. It's reasonably effective on a preventive basis, but won't rescue a crop that's already got a serious disease problem.
Black rot. The frogeye leaf spot phase has been common for the last couple of weeks, particularly on Cortlands or other varieties containing mummies in the tree. These leaf infections aren't very meaningful in terms of supplying new inoculum for fruit rot, but they do serve as good indicators that other, important sources of inoculum are present (mummified fruits, dead twigs and branches) and capable of causing fruit rot. Fruit are susceptible from the time they form until harvest. Infection requires rain and is favored by warm temperatures (the literature reports a 9-hr wetting requirement at the optimum temeperatures of 68-76¡F). At this point in the season, fruit infections look like small, black pimple-like lesions, which won't start expanding until the fruit ripen. Where control is needed, combine a benzimidazole (Benlate, Topsin-M) with captan. Ziram is a possible, but inferior, substitute for captan in blocks using summer oils.
Sooty blotch/fly speck. Not showing up yet, but they should be incubating right now. Continued wet weather will greatly shorten the incubation period, and provide the possibility for secondary spread once the first infections develop. Captan's notoriously weak against fly speck, so make sure that it's tank-mixed with a benzimidazole (the most effective materials against SB/FS). Ziram's a good substitute for the captan component of a benzimidazole mix.
Fire blight. Strep sprays seem to have helped where they were used during bloom. Control of subsequent shoot blight infections is tough, and everybody has their own philosophy. However, there's one important new piece of information to be aware of: last year, Jay Norelli and Herb Aldwinckle conclusively demonstrated that rootstock infections (M.9, M.26) can occur very easily when succulent sucker growth becomes blighted and the bacteria move the short distance from these shoots down into the wood where they originated. These infections are fatal. Thus, perhaps the most important fire blight control measure at this time of the year is to remove/control sucker growth on susceptible rootstock clones.
By: Art Agnello, Entomology, Geneva
The Pearleaf Blister Mite, Phytoptus pyri, is a sporadic pest of pears that does not normally show up in commercial pear orchards, but is a fairly common problem in home plantings. The adults are very small and cannot be seen without a hand lens; the body is white and elongate oval in shape, like a tiny sausage. The mite causes three distinct types of damage. During winter, the feeding of the mites under the bud scales is believed to cause the bud to dry and fail to develop. This type of damage is similar to and may be confused with bud injury from insufficient winter chilling. Fruit damage is the most serious aspect of blister mite attack. It occurs as a result of mites feeding on the developing pears, from the green-tip stage through bloom, causing russet spots. These spots, which are often oval in shape, are usually depressed with a surrounding halo of clear tissue. They are 1/4 to 1/2 inch in diameter and frequently run together. A third type of injury is the blistering of leaves; blisters are 1/8 to 1/4 inch across and, if numerous, can blacken most of the leaf surface. Although defoliation does not occur, leaf function can be seriously impaired by a heavy infestation.
The mite begins overwintering as an adult beneath bud scales of fruit and leaf buds, with fruit buds preferred. When buds start to grow in spring, the mites attack developing fruit and emerging leaves. This produces red blisters in which female blister mites then lay eggs. These resulting new colonies of mites feed on the tissue within the protection of the blister, but can move in and out through a small hole in its center. The mites pass through several generations on the leaves but their activity slows during the warm summer months. The red color of the blisters fades and eventually blackens. Before leaf fall the mites leave the blisters and migrate to the buds for the winter.
A fall spray is recommended sometime in October, when there is no danger of frost for at least 24-48 hr after the spray. Use Sevin 50 WP (2 lb/100), or 1-1.5% oil plus either Diazinon 50WP (1 lb/100 gal) or Thiodan 50WP (1/2-1 lb/100 gal). A second spray of oil plus Diazinon or Thiodan, in the spring, just before the green tissue begins to show, will improve the control.
Codling moth development in the state has progressed beyond the appropriate point for control of the 1st generation larvae; we will begin advising of the second brood management window when it approaches later in the season.
Although we haven't seen too many yet, we assume that obliquebanded leafroller egg masses are being laid and we've therefore been keeping track of their presumed development in various locations, as cued by the first moth catches at those sites. The past week saw rather cooler weather than normal in a few instances, so we haven't yet accumulated enough heat units to warrant a control spray in those orchards waiting for the first hatch. In the more advanced sites, this event could happen by the end of the week, so growers intending to use a 3-spray program (of Confirm, Lorsban, Dipel, etc.) should note their local temperature readings this week and add appropriate DD's to the OBLR developmental totals we've calculated as of this morning, 6/24; first hatch is predicted at approximately 360 DD:
Highland - 392.4 Albion - 290.3 Sodus - 289.2 Lyndonville - 196.4 Williamson - 176.3 Geneva - 173.0 Appleton - 168.0
SAN JOSE SCALE
The San Jose scale (SJS) is a pest of tree fruit that attacks not only apple, but also pear, peach, plum, and sweet cherry. The minute SJS adult males emerge in the spring from beneath scale covers on the trees, usually during bloom, and mate. The first of this year's crawlers should be showing up any day now. The females produce live crawlers within 4-6 weeks of mating; these are bright yellow, very tiny insects resembling larval spider mites. About 24 hours after birth, the crawlers have walked or drifted to new sites and settled in by inserting their mouthparts into the tree and secreting a white waxy covering that eventually darkens to black.
SJS infestations on the bark contribute to an overall decline in tree vigor, growth, and productivity. Fruit feeding causes distinct red-purple spots that decrease the cosmetic appeal of the fruit. Control measures for SJS are recommended when the scale or their feeding blemishes have been found on fruit at harvest during the previous season. Insecticidal sprays are most effective when directed against the first generation crawlers, specifically timed for the first and peak crawler activity, which are usually 7-10 days apart.
The most reliable method of determining first appearance of the crawlers in your specific area is by putting sticky-tape traps on the tree limb near encrusted areas and checking them at least twice a week. We are just about at the predicted time for this event, based on a degree-day accumulation of 310 (50¡F base) from the date of first adult catch (6/6 in Geneva this year). Effective materials for SJS control include Lorsban 50WP, Provado (note that this is a newly labelled use; see article below), Guthion, Imidan and Penncap-M. These sprays may also help in the control of OBLR, apple maggot, and codling moth. Coverage and control are generally better if the pesticide is applied dilute and in every row. SJS is frequently a problem in larger, poorly pruned standard size trees that do not receive adequate spray coverage. Dormant or delayed-dormant sprays of oil, or 1/2-inch green applications of Lorsban 4EC or Supracide will help prevent populations from getting established. Early season pruning is important for removing infested branches and suckers, as well as for opening up the canopy to allow better coverage in the tree tops where SJS are often concentrated.
PROVADO LABELLED FOR PEARS
We have been informed that Provado 1.6F, which previously had a registration only for apples in N.Y., was last week granted a state label for pears as well; San Jose scale was also added to the apple label. This product is now an option for the control of pear psylla, mealybugs (such as Comstock mealybug), San Jose scale and aphids on pears, at a rate of 5 oz/100 gallons (20 oz/A maximum per application). As with apples, allow at least 10 days between applications and observe a PHI of 7 days.
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
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