top of page

April 2019

As dormant sprays are wrapping up for many areas, I’d like to remind growers of some other important spray timings to keep in mind. Whether you missed the ideal delayed dormant spray time for your area or just want to stay on top of some critical pest and disease issues, here are some things to keep in mind.


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 Asana/Zyrate or Dimilin with your dormant oil spray is often effective at gaining control over this critter. These materials are able 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 during the period from bloom to 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 of 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, two sprays timed at half inch green and pink are ideal. With mildew sensitive varieties, protection will need to be maintained 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. The most commonly used in our area are Bio 90 or an oil of some type.

Oriental Fruit Moth

OFM has been a pest in the Palisade area for a long time. The insectary has been raising parasitic wasps for OFM since 1946. This pest seems to like the area up close to the mouth of the Colorado River canyon in what’s known locally as the Vinelands district, and there it stays. It’s long been a curiosity to me why OFM hasn’t moved west across Orchard Mesa and on into Delta county.

OBLR (Obliquebanded Leafroller) for a number of years was a major pest causing extensive damage in Delta county pome fruit orchards. Then one season it just disappeared. I’ve not found OBLR damage for years.

Here’s a link to a bit of info on OBLR:

Each year Cropworx runs a trap line across the various regions of our fruit industry. We use these traps to monitor pest populations and also biophenometer and weather station data to help determine treatment timings. This year we will add OFM & OBLR traps to the lineup! Want to have advanced notice of a sneak attack coming to your orchard? Be proactive by placing a few pheromone traps for each of these pests in a few different blocks. This is a far less expensive program than dealing with an infestation.

Weed Burn Down

Fusilade is a grass killer. When Fusilade is used in combination with the broadleaf herbicide Aim, you have a tank mix that does the same job as Gramoxone. The benefit to using this mix is that neither material requires the use of a respirator and there’s no toxicity issues to the applicator. The down side to this program is that the mix is twice the cost per acre as Gramoxone. Depending on the number of acres you’re spraying it may not take long to pay for a respirator fit test kit.

Lifeline (Forfeit, Rely, Cheetah) also works as a burndown. Lifeline herbicide is a non-selective, post-emergent herbicide that provides broad spectrum weed control of some of the most challenging weeds; including control of glyphosate resistant marestail, hairy fleabane, malva, and filaree. Utilizing a unique mode of action, Lifeline inhibits glutamine production in the weeds which leads to a breakdown in photosynthesis. This makes Lifeline an excellent choice when developing your overall weed resistance management strategy and also does not require a respirator.

We’ve been getting a few calls regarding the law on the use of respirators. Upon visiting with Audrey Cooper from the Colorado Department of Ag, her advice was to do your own “fit test” using a kit from Gemplers. The kit can be purchased for approximately $150. Here’s a few links to information related to respirators.

Respirator resources:

WPS Respiratory Protection Guide:

Grand Junction Respirator Medical Evaluation and Fit Testing

Work Partners Occupational Health 970-241-5585

· Bring the OSHA Medical Evaluation Form with them - already filled out

· Bring their own mask, respirator with them

Foresight Family Physicians Occupational Health Department 970-241-9606

· Bring OSHA Medical Evaluation Form completed with them

· Foresight will supply the respirator to be fit tested in

· They receive a card identifying which type they were fit tested on

The following is a link to a Cytospora update from USU Extension, referencing CSU's research:

Give it a read!

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!



bottom of page