Contents
Aphids, Including Spirea Aphid
European Red Mite, Twospotted Spider Mite
Tarnished Plant Bug, Pear Plant Bug
Table 36. Pesticide Spray table—Pears.
Table 37. Growth Regulator Uses in Pears.
Diseases
Fabraea Leaf Spot
• Biology & Cultural
[1.1] Bosc and Seckel are much more susceptible than Bartlett.
• Pesticide Application Notes
[1.2] It is important to prevent the establishment of early primary infections. Sprays should start at green cluster if the year is wet and disease was prevalent last year; otherwise, wait until white bud. Continue sprays at 10- to 14-day intervals through 1st or 2nd cover. In orchards with high inoculum, apply a mancozeb spray at 7-day intervals after petal fall until reaching either the 77-day PHI or the limit on the number of sprays per season. A 3-wk summer spray schedule will normally maintain control if early infections have been prevented. Summer sprays of Sovran or Flint to control scab or sooty blotch will also control Fabraea leaf spot. Pear psylla can facilitate the spread of leafspot during summer, so controlling psylla is important in high-pressure orchards. Using summer oils to suppress pear psylla may also suppress spread of Fabraea leaf spot during late summer.
Fire Blight
• Biology & Cultural
[2.1] Fire blight is an even more serious disease on pears than it is on apples. In general, the control strategies recommended for apples apply equally to pears. Bartlett, Bosc, Clapps Favorite, and Gorham are all extremely susceptible varieties. D’Anjou is slightly less susceptible, but comparable to the most highly susceptible apple variety; Seckel is considered moderately susceptible. Refer to the discussion of this disease in the “General Pest Management Considerations for Apples” section.
[2.2] The best program for reducing summer spread of fire blight is good psylla control.
Refer to the reference materials list at the end of this publication for a Fact Sheet containing more details on the biology and management of this pest.
• Pesticide Application Notes
[2.3] While specifically labeled for control of pseudomonas blight, a copper spray also will assist with control of fire blight. However, it will not eliminate the need for streptomycin at bloom. It is effective in reducing the population of overwintering fire blight bacteria, and is a useful component in an overall fire blight control program. Thorough coverage of the entire tree is necessary for maximum effectiveness, so high-gallonage sprays are preferred. Leaf burning may occur if applied beyond bud burst, especially under slow drying conditions. The oil should be added at a rate of 1 qt per 100 gal of actual spray solution in the tank (i.e., do not concentrate the oil). If using Bordeaux mix, prepare as described in the “Fungicides”section of “Characteristics of Crop Protectants.” Add the oil after adding lime, but before making up to volume. The 1 qt of oil is added to increase the efficiency of the copper compounds and is not sufficient for good psylla control. A separate oil application can be made for psylla, or 3 gal of oil can be used with the copper sprays. Several other commercial copper formulations in addition to those listed are labeled for this use on pears. Although they have not been tested, research on other crops suggests that most copper formulations should give comparable rates of control at comparable rates of metallic copper.
[2.4] Streptomycin is not recommended for routine summer use, but is strongly recommended for use within 24 hr after the start of a hailstorm.
[2.5] Bloomtime Biological is labeled for blossom blight control in pears. This biopesticide is consistently less effective than streptomycin, but may be a viable option in orchards with low levels of fire blight inoculum and during environmental conditions indicative of a low risk of infection. Currently, this product has not been evaluated on pears in New York. However, in NY apple orchards, this product has been shown to provide up to 50% control when applied during bloom compared to streptomycin.
Pear Scab
• Biology & Cultural
[3.1] Seckels are very susceptible to scab; Bosc and D’Anjou, somewhat less so; Bartlett is relatively resistant.
• Pesticide Application Notes
[3.2] If scab developed the previous year, sprays should begin at green cluster and continue at 7- to 10-day intervals through 2nd cover. In blocks with little history of scab, sprays from white bud through 1st cover should provide sufficient protection. Additional cover sprays will be necessary if scab becomes established and the season remains wet. Use of Topsin M and Thiophanate-methyl should be limited during the early season if substantial use is anticipated later in the season for control of sooty blotch and Fabraea leaf spot. Note: Topsin M and Thiophanate-methyl have a 3-day (76 hr) REI.
[3.3] Mancozeb fungicides are more effective than ferbam or ziram. It is labeled for use on pears in one of two different ways: (i) at a rate of 1.5–2 lb/100 gal (maximum 6 lb/A, no more than 24 lb/A per year), not to be applied after bloom; OR (ii) at a reduced rate of 3 lb/A (maximum 21 lb/A per year), which may be applied to within 77 days of harvest.
The latter program is particularly valuable where Fabraea leaf spot and sooty blotch must be controlled in the early summer. It is illegal to combine or integrate the two treatment regimes or to use any mancozeb sprays after bloom if any of the earlier sprays were applied at more than 3 lb/A of formulated product.
[3.4] Sovran and Flint are excellent protectants, and will be most reliable when used in this manner. They have 48–72 hr post infection activity against pear scab. They significantly reduce spore production from the lesions that develop when the fungicides are applied several days after the start of an infection period. They are not registered for control of Fabraea leaf spot but they control leaf spot when applied during the summer. They provide good control of black rot on apples, but they are not registered for control of this disease on pears and experience with control of black rot on pears is lacking. The strobilurins are prone to resistance development, and it appears that resistance to one member of this class of materials confers resistance to other products in the class (cross-resistance). The primary strategies for reducing the resistance risk are to: (i) rotate these materials with unrelated fungicides; and (ii) limit the number of seasonal applications of a strobilurin (e.g., three per year).
CAUTION: Sovran has caused moderate to severe phytotoxicity (leaf burning) on several sweet cherry varieties when sprayed directly onto them at high labeled rates. The most sensitive varieties were: Somerset, Sweetheart, Valera, Van, and Vandalay; these varieties might also be injured by spray drift containing Sovran. Minor to moderate injury occurred on Cavalier, Coral Champagne, Emperor Francis, Royalton, Schmidt, Summit, and Viva; there is less danger of injury due to spray drift on these varieties. Many other sweet and sour cherry varieties (including Bing, Brooks, Cashmere, Gold, Hardy Giant, Hartland, Hedelfingen, Hudson, Kristin, Lapins, Lambert, Montmorency, Napoleon, Nelson Black Sweet, Rainier, Royal Ann, Sam, Stark Crimson, Stella, Sue, Tehranivee, Tulare, Ulster, Vega, Vic, Viscount, and Windsor) showed no injury when sprayed directly with high labeled rates. The Sovran manufacturer recommends: (i) Do not apply Sovran near or allow drift onto cherries in the highly sensitive group (Somerset, etc.); and (ii) thoroughly rinse spray equipment (tanks, hoses, nozzles) after spraying Sovran and before using this equipment on sensitive cherry varieties.
[3.5] Note that Rubigan is not labeled until petal fall (potential fruit shape problems if used earlier). Rubigan has 72–96 hr postinfection activity but limited protectant activity. It should be combined with mancozeb to improve fruit scab control and protect against other diseases such as sooty blotch and Fabraea leaf spot. Note the mancozeb restrictions listed in [3.3].
[3.6] The risk of primary scab is greatly reduced after 1st or 2nd cover. Where scab has been well controlled and there is no history of leafsot problems, it is possible to extend fungicide spray intervals to 14–21 days after the 3rd cover has been applied. If these diseases have not been controlled, fungicides should be applied at 10- to 14-day intervals throughout the summer, except during drought periods. Observe mancozeb restrictions detailed in [3.3].
Sooty Blotch
• Biology & Cultural
[4.1] Sooty blotch develops gradually during periods of rain, dew, and very high humidity. The disease is favored by frequent showers, poor air circulation, and nearness to woods and brushy hedgerows (sources of inoculum). Fungicide control programs should begin about 1st cover, depending upon weather and inoculum pressure. Pruning to improve air circulation through the canopy will reduce the total fungicide need in most years. See [3.3] above, and remark [10.1] in the General Pest Management Considerations for Apples section for additional information about sooty blotch.
Insects and Mites
Aphids, Including Spirea
Aphid
• Pesticide Application Notes
[5.1] Do not exceed 2 applications of *Thionex per season.
[5.2] †*Calypso applied at petal fall will also control Comstock mealybug.
Codling Moth
• Biology & Cultural
Refer to the reference materials list at the end of this publication for a Fact Sheet containing details on the biology and management of this pest.
• Pesticide Application Notes
[6.1] Summer sprays should be timed to start approximately at the 10% hatch point, 175–200 DD (base 45°F) after the first adult catch of the second brood, with a second application in 10–14 days. Use of a non-ionic surfactant is recommended with Assail. Pyrethroid insecticides applied during summer against pear psylla will control codling moth. Use Sevin at 1 lb rate. Suggested action threshold: when commercial trap catch exceeds that in abandoned orchard and night temperature is at least 55°F.
• Biological & Non-chemical Control
[6.2] Better control is obtained when pheromone disruption begins with the first generation of the season; regardless, products for disruption should be applied before first flight of the generation being targeted. Residual field life of CM-F may require re-application after 14 days. Insecticide sprays or double the rate of pheromones may be needed in border rows of orchards adjacent to sources of adult immigration or in other high pressure situations.
Comstock Mealybug
• Biology & Cultural
Refer to the reference materials list at the end of this publication for a Fact Sheet containing details on the biology and management of this pest.
• Pesticide Application Notes
[7.1] Sprays recommended at petal fall and 7d later, against newly emerged crawlers. Research suggests that treatments against 2nd generation crawlers are more effective, but petal fall sprays may be of use in keeping populations low. †Actara and †*Calypso will also control plum curculio and pear psylla when applied at petal fall; not registered for use in Nassau or Suffolk Counties. Do not make more than one application of †Actara per season.
[7.2] Two sprays recommended for the 2nd generation, 7 days apart, against newly hatched crawlers. Begin approximately Aug. 1 in Hudson Valley, one week later in Western New York. †Actara and †*Calypso not registered for use in Nassau or Suffolk Counties; do not make more than one application of †Actara per season. Suggested action threshold: 5% calyx infestation of previous year’s crop.
European Red Mite, Twospotted
Spider Mite
• Biology & Cultural
Refer to the reference materials list at the end of this publication for a Fact Sheet containing details on the biology and management of this pest.
• Pesticide Application Notes
[8.1] Applications advised as needed in summer. Acramite and Apollo are not effective against rust mite. Kanemite and Kelthane limited to a maximum of 2 applications per season; not registered for pear rust mite. Use 4 oz of *Carzol if treatment is for rust mite only. Use 10.7 oz of †Nexter if treatment is only for twospotted spider mite; use lower rate for European red mite. †Nexter not registered for use in Nassua or Suffolk Counties. †Nexter, Savey and Acramite limited to 1 application per season. Suggested action threshold: 6 motile forms/leaf.
Green Fruitworms
• Biology & Cultural
Refer to the reference materials list at the end of this publication for a Fact Sheet containing details on the biology and management of this pest.
• Pesticide Application Notes
[9.1] Growers can usually wait until petal fall to assess the need for treatment. Only 0.9 lb AI/ acre of *Lannate permitted per season. It is recommended that pyrethroids not be used more than 1–2 times per season in any orchard. Suggested action threshold: 3 larvae/tree on large trees (27–40 trees/A); 1 larva/tree at density of 140 trees/A.
Obliquebanded Leafroller
• Biology & Cultural
Refer to the reference materials list at the end of this publication for a Fact Sheet containing details on the biology and management of this pest
• Pesticide Application Notes
[10.1] Spray recommended when last petals are falling. Only 1.8 lb AI/acre of *Lannate permitted per season. Will also help control Comstock mealybug. A pyrethroid applied now against pear psylla will also control obliquebanded leafroller. Suggested action threshold: 5–10% infested clusters.
[10.2] For 1st summer brood in July, begin applications approximately 360 DD [base 43° F] after 1st adult trap catch. Only 1.8 lb AI/acre in 2 applications of *Lannate permitted/season.
Pear Midge
• Pesticide Application Notes
[11.1] Two spray applications between the swollen bud and white bud stages.
Pear Psylla
• Biology & Cultural
Refer to the reference materials list at the end of this publication for a Fact Sheet containing details on the biology and management of this pest.
• Pesticide Application Notes
[12.1] To inhibit egg-laying by psylla, apply oil as soon as first eggs are laid in the spring; timing is especially critical (not effective if >20% of spring oviposition has occurred). Make 2nd application in 7 days if adults are still present. If 2 sprays are anticipated, drop rate to 2 gal for both. The 3 gal rate can also help reduce overwintering populations of European red mite, pearleaf blister mite, and Comstock mealybug. Suggested action threshold for pear psylla: 1 egg in a 3-minute inspection of buds.
[12.2] Apply insecticide from swollen bud through white bud. Pear rust mite may build up with repeated pyrethroid use. Seasonal maximum for *Ambush and *Pounce is 2 lb a.i./A; for *Asana, up to 0.2 lb a.i. during the dormant to white bud stage and up to 0.225 lb a.i. between bloom and harvest (but no more than 0.375 lb total a.i./Acre per season). Esteem may be applied once prebloom at 5 fl oz/A, or once prebloom and once at petal fall at 4-5 fl oz/A. Suggested action threshold before white bud: 6–10% of spurs with eggs.
[12.3] M-Pede can provide suppression when used in a seasonal program. Uniform drying conditions are required to prevent droplet residue on fruit; short residual period.
[12.4] One spray of oil at 2 gal rate, or 2 sprays at 1 gal rate, recommended through tight cluster.
[12.5] †Nexter limited to a maximum of 1 application per season. Esteem may be applied once prebloom at 5 fl oz/A, or once prebloom and once at petal fall at 4-5 fl oz/A. Suggested action threshold after fruit set: Avg of 1–2 nymphs per terminal leaf. *Agri-Mek can be used anytime from petal fall to about 4 weeks afterward, but is most effective when applied before foliage begins to harden off, generally within the first 2 weeks after petal fall. Should be applied in combination with a horticultural spray oil (not a dormant oil) or other penetrating surfactant. †Actara and †*Calypso will also control plum curculio and Comstock mealybug when applied at petal fall; not registered for use in Nassau or Suffolk Counties. Do not make more than one application of †Actara per season.
[12.6] Frequent applications (7–10-day intervals) of Surround and maximal coverage (minimum of 100 gal/A) are advised in New York while there is active foliar growth.
• Pesticide Resistance
[12.7] Variable levels of pear psylla tolerance or resistance to pyrethroids have been seen in New York, so growers should alternate use of pyrethroids with other materials to delay the development of resistance in their orchards. The preferred strategy would be to withhold their use until (and unless) needed in the summer.
Pear Rust Mite
• Pesticide Application Notes
[13.1] In blocks with a history of rust mite infestations, a preventive petal fall spray might be advisable. Kelthane limited to a maximum of 2 applications per season. †Nexter limited to a maximum of 1 application per season. See [8.1].
Pearleaf Blister Mite
• Pesticide Application Notes
[14.1] A spray of oil plus diazinon or oil plus *Thionex, in the spring, just before the green tissue begins to show, will benefit most control programs. See [12.1].
[14.2] A fall application post-harvest, when there is no danger of frost for at least 24-48 hr after the spray.
Plum
Curculio
• Biology & Cultural
Refer to the reference materials list at the end of this publication for a Fact Sheet containing details on the biology and management of this pest.
• Pesticide Application Notes
[15.1] Sprays recommended at petal fall and 10 days later. 1st brood codling moth is also controlled by these materials; (see [6.1] for 2nd brood control). *Imidan also controls fruit tree leafroller. †Actara will also control pear psylla and Comstock mealybug when applied at petal fall; not registered for use in Nassau or Suffolk Counties. Do not make more than one application of †Actara per season.
Redbanded Leafroller
• Biology & Cultural
Refer to the reference materials list at the end of this publication for a Fact Sheet containing details on the biology and management of this pest.
• Pesticide Application Notes
[16.1] Two sprays, from mid-July to early August, for 2nd brood control in problem blocks; note PHI restrictions.
Tarnished Plant Bug, Pear
Plant Bug
Refer to the reference materials list at the end of this publication for a Fact Sheet containing details on the biology and management of this pest.
• Pesticide Application Notes
[17.1] Recommended spray timing is from green cluster to white bud. Suggested action threshold: plant bugs—3 bleeding sites/tree, or a cumulative catch of 7 adults by white bud stage (white sticky-board trap). See [12.7].