2018 Crop Protection Guide for Tree Fruits in Washington

Apple Programs

Friday, February 22, 2019

Apple at Bloom

See General Recommendations for guidelines on table use. Read all product labels carefully.
See text section on hazards to bees. Do not apply Class I bee toxicants when blossoms are open or after hives have been placed in the orchards.

= link to additional information in Orchard Pest Management



Except where noted, rates are amount per acre
Efficacy if estimate is available (+ to ++++)
Assail 70WP

1.7-3.4 oz
-- -- --
12 h

7 d

Bacillus thuringiensis subsp. kurstaki -- -- See label
-- 4 h0 d11B2  
CM pheromone dispensers -- See label -- -- none listedNL   
Intrepid 2F
-- --
16 fl oz
4 h

14 d

Actigard 50WG
-- -- --
1-2 fl oz

12 h h

0 d

Blossom Protect
Aureobasidium pullulans
-- -- --
1.25 lb



copper octanoate
-- -- --
3-4 qt

4 h

0 d

DoubleNickel 55
Bacillus amyloliquefaciens strain D747
-- -- --
See label

4 h

0 d

Kasumin 2L
-- -- --
64 oz

12 h

90 d

copper hydroxide
-- -- --
3-4 qt

48 h


Serenade Opti
Bacillus subtilis strain QST 713
-- -- --
20 oz

4 h


oxytetracycline -- -- -- See label12 h60 d41

Campylomma: While the listed materials will kill Campylomma at any time, applications must go on at pink or bloom to prevent damage -- petal fall is too late. Treat as soon as the action threshold for a given cultivar is reached (see http://treefruit.wsu.edu/crop-protection/insect-mite-pests/campylomma/ for more information).

Codling moth: Pheromone treatments typically need to be supplemented with insecticides to achieve acceptable levels of control. Any insecticide recommended for control of codling moth can be used as a supplement to pheromone treatments. Timing of different insecticides used as supplements for codling moth control in pheromone treated orchards depends on the stages they impact, eggs or larvae. Refer to the Petal-fall, 14-28 days after Full Bloom, and Late Spring and Summer timing periods for specific recommendations of supplemental insecticides.

Leafrollers (Pandemis, Obliquebanded): If planning to apply insecticides for control of these pests post-bloom then insecticide treatments should not be applied at this time.  

Fire blight: There is a risk of fire blight infection any time there are flowers on the tree, the weather is warm, and wetting occurs. Watch for and protect secondary blossoms during the three weeks after petal fall, which is the most common time of fire blight infection.

Early bloom. Apply biologicals (Blossom Protect) during early bloom. If fire blight was in the orchard last year apply two applications of the biological. Reapply biological a second time if lime sulfur was applied (Lime sulfur is antimicrobial and kills biological).

Full bloom to petal fall. Watch the model. If an infection event occurs, apply an antibiotic as soon as possible, but within 24 hours of infection (usually wetting of flowers). Repeated antibiotic sprays may be necessary during extended high or extreme risk periods. Best results are obtained when applied within 24-hour window before flower wetting during a high infection risk period. Beneficial only for flower infection prevention. Product used must contact the interior of the flowers in sufficient water and approved wetting agent to completely wet the interior. One pound of any 17% oxytetracycline product per 100 gallons gives a 200 ppm solution. Kasugamycin is another effective antibiotic. Some trials have shown that a full rate of Kasumin and a half rate of oxytetracycline provides excellent control. Applications of less than 100 gal/A can be effective on small trees if flower interiors are well covered, but do not drop the ppm below 200 (oxytetracycline). Application by ground equipment on each row is highly recommended. Application of antibiotics by aircraft is not recommended. Many fire blight bacteria in the Pacific Northwest are resistant to streptomycin, another registered antibiotic.

Organic. Prebloom. Fixed copper sanitation if fire blight was in the orchard last year. Early bloom. Lime sulfur plus oil.  One to two applications of biologicals (Blossom Protect). Reapply after lime sulfur which is antimicrobial. Depending on the cultivar russet risk and the CougarBlight model risk follow with Bacillus subtilis (Serenade Optimum) (most fruit safe) every 2-5 days during flower/petal fall or copper hydroxide/octanoate (Cueva/Previsto) every 5 to 6 days (This option is less fruit safe for russet).

Assail 70WP: Use higher rates for high populations.

Intrepid 2F: Some leafroller populations have developed resistance to Intrepid and in these situations the level of control can be significantly reduced.

CM pheromone dispensers: Most apple growers in Washington use pheromones to help control codling moth. Pheromone dispensers must be in place before the first moth flight, that is prior to bloom. The number of dispenser units per acre will depend on the product used and pest pressure.

Hand-applied dispensers should be placed within the top 2 feet of the tree canopy. It is strongly recommended that full label rate of any hand-applied pheromone dispenser be used. Reducing the rate of hand-applied dispensers per acre can reduce efficacy and result in more damage from codling moth or require the use of more insecticides to achieve acceptable control. 

Some apple growers are using aerosol pheromone emitters (CheckMate CM-O Puffer and Isomate CM MIST) to control codling moth. This technology is used at a rate of one pheromone emitter per acre. WSU research has shown that the aerosol emitter technology works as good as a full rate (400 dispensers per acre) of a hand-applied dispenser technology.  However, the borders of orchards need to be treated with hand-applied pheromone dispensers to cover gaps resulting from the number of aerosol emitters that are applied per acre.

Actigard 50WG: For bloom applications: Apply 1 - 2 oz/A in a tank mix with a fire blight treatment (generally an antibiotic) that is standard in your area. This is generally 2-3 applications between 20% bloom and petal fall depending on the environmental conditions. Do not apply closer than a 7 day interval.

After removing cankers: Mix 1 oz Actigard in 1 quart of 1% penetrant. Apply to the branch area immediately below the canker after cutting 12-18 inches below the canker. In small trees the application can be made to the central leader below the branch where fire blight was cut.

DoubleNickel 55: See label and space between rows to select the corresponding rate. Efficacy may vary based on disease pressure.


Tree Fruit Research & Extension Center, 1100 N Western Ave, Washington State University, Wenatchee WA 98801, 509-663-8181, Contact Us