top of page

March 2020

As we prepare to rush headlong into the season, here’s a reminder of the importance of horticultural oil sprays and timing! The dormant/ delayed dormant oil sprays are typically the first line of defense at the beginning of the season. The dormant season is a critical period for various pest management activities:

· Several key insect and mite pests overwinter in orchards and are vulnerable to sprays.

· Because leaves are off the tree, good spray coverage is easier to obtain.

· Beneficial insects and mites are less affected by sprays during dormancy.

· Several pests are concentrated on the twigs and shoots, making dormant season an excellent time for monitoring and assessing their populations.

Dormancy is generally defined as the period from leaf fall until growth resumes in spring. Delayed dormancy is the period from the resumption of growth, indicated by bud swell until green tip.

Dormant versus delayed-dormant treatments. If the main target is San Jose scale, then a dormant timing (before bud swell) for treatment is usually best. It should be noted that San Jose scale has been found in some orchards this past season, so this spray will be critical for early control!! Control of peach silver mite and peach twig borer larvae in hibernacula is effective at either timing. European red mites (eggs), two spotted spider mites and obliquebanded leafroller larvae are best controlled using delayed-dormant timing.


In peaches, dormant oil sprays aren’t enough to smother and kill the overwintering Peach Twig Borer (PTB) nestled in its hibernacula (Latin, "tent for winter quarters"). The hibernaculum is typically located in crotches of 1 to 3 year old wood, in pruning wounds, or in deep cracks in bark. The overwintering site is marked by a chimney of frass (bug turds) and is especially noticeable when first constructed or before winter rains set in. If you experienced PTB damage in your fruit or know that there is a presence in your orchard of this pest, adding 8 oz of Asana (per acre) with your dormant oil spray is often effective at gaining control over this critter. The Asana is stout enough to penetrate the hibernaculum and kill the pest before bloom occurs. If not controlled, the PTB migrates up twigs and branches where they attack newly emerged leaves, blossoms, and shoots. As shoots elongate, larvae mine the inside causing the terminals to die back. Dead shoots are known as shoot strikes or flags.

If you miss the delayed dormant spray timing, there is another opportunity to control PTB, and that comes between full bloom and shuck split. Within an IPM program, the preferred management strategy for peach twig borer is well-timed treatments of environmentally sound insecticides around bloom time. These include Dipel, Entrust or Success, Intrepid, Delegate and Dimilin. Delegate, Success and Entrust are great choices as they provide control over thrips as well. Bloom time sprays on peaches are a great time to throw in a fungicide for coryneum blight and something for nutrition as well!


Powdery mildew is distinguished by superficial, white powdery growth on leaves and shoots that result in the stunting and distortion of young growth. Infected fruit are stunted and russetted, and fruit set may be reduced. This is a major foliage disease of apples. The fungus overwinters in terminal buds that are white, flattened, and pointed. Disease development is favored by warm days and cool, moist nights.

To prevent buildup of the fungus and damage to the crop early in the season, sprays timed at half inch green and pink are ideal. If powdery mildew continues to be a problem in the orchard, apply additional treatments until terminal growth ceases. Take advantage of your time spent spraying for mildew by adding some nutrition. At pink, it’s a great time to throw in any or all of the following; Urea, Calcium, 20-20-20 and maybe some boron to help with fruit set.

If woolly apple aphids were a problem, keep in mind they’re coming out of the ground and heading up the tree at about half inch green. A slurry of Diazinon mixed with a sticker sprayed on the trunks is effective at preventing/ killing them before getting to the canopy. This job is best done with a handgun. The more water you apply the better it works. Though it may not be enough to eliminate the problem, it certainly gives you a head start on control early in the season.

Surfactants, also called wetting agents and spreaders, physically alter the surface tension of a spray droplet. For a pesticide or nutrient to perform its function properly, a spray droplet must be able to wet the foliage and spread out evenly over a leaf. Envision a drop of water on the kitchen counter and how it sits in a “dome” shape. Surfactants cause the dome to flatten out. They enlarge the area of product coverage, thereby increasing the plants exposure to the product applied. Surfactants are particularly important when applying products to waxy or hairy leaves. Without proper wetting and spreading, spray droplets often run off or fail to adequately cover these surfaces. Surfactants help pesticide sprays penetrate plant cuticles. Every tank of spray that I apply each season has some type of surfactant in the mix. The most commonly used in our area are Bio 90 or an oil of some type.

Coryneum Blight

The main symptoms of shot hole on peach occur on twigs and buds, but fruit lesions may develop when spring weather is wet. Twig symptoms first appear as small, purplish black spots. These turn brown as they enlarge, often having a light center with a purplish brown margin. Tiny, dark brown bumps develop at the center of each lesion.

Fruit and leaf symptoms look much like those of twig lesions. They are small spots, purplish at first, and turning light brown in the center as they enlarge. Sporodochia form in leaf lesions but not in fruit lesions. Leaf lesions may be surrounded by a light green or yellowish zone; in many cases the brown tissue in the center will fall out, leaving the "shot hole" that gives the disease its name.

Wilsonomyces carpophilus survives on infected twigs and buds. Spores are produced throughout winter and are spread by splashing rain and wind. The disease is favored by prolonged wetness in fall to mid-winter (twig blight). Summer rain or sprinkler irrigation encourages fruit infection. There is more infection low in the tree where fruit stay wet longer.

Barrels/ Shuttles

Once again, throughout the season the Cropworx crew works hard to keep your needs met with timely deliveries and also removal of empty OIL barrels and shuttles. These barrels/ shuttles go through a rigorous cleaning process and are then put right back into rotation with more material. They are costly to replace and each year more barrels/ shuttles seem to disappear. The cost of these units are not passed along to the customer, and we need your help in getting them back after they’re empty. Please help us in our efforts to save the barrels/ shuttles and let them have long, illustrious life cycles meeting your needs with the chemicals we provide. If you have empty barrels/ totes please let us know!

Unfortunately we are no longer able to take lime sulfur barrels or shuttles back!

“You cannot help the poor by destroying the rich.

You cannot strengthen the weak by weakening the strong.

You cannot lift the wage earner up by pulling the wage payer down.

You cannot further the brotherhood of man by inciting class hatred.

You cannot build character and courage by taking away people’s initiative and independence.

You cannot help people permanently by doing for them what they could and should do for themselves.”

~Abraham Lincoln



bottom of page