Delayed Dormant Sprays in Almonds and Stone Fruit
Applying a dormant or delayed dormant spray to tree fruit orchards can be a great way to get your pest management program off to the right start next season. It reduces overwintering populations of key pests and provides a protective barrier before bud break.
The cornerstones of dormant spray programs are copper and oil. Nordox 75WG is an ideal copper formulation for dormant application. The OMRI listed cuprous oxide-based formula will adhere very effectively to dormant spurs and buds and resist wash-off throughout the winter. This, coupled with the slow release of copper ions, means there will be a protective copper residue through bud break in the spring. Apply 5-13 lb/ac to control Scab in almonds, Peach leaf curl, and Shot Hole in almonds or stone fruit. A rate of 4-5 lb/ac can help control early development of bacterial spot.
Dormant oil sprays are often made with cheaper heavy “dormant oil” formulations. TriTek can be a better fit especially in delayed dormant applications after buds have started to swell and there may be concern of phytotoxicity. TriTek is an inverse emulsion formulation meaning when it is diluted in spray tank, the oil droplets are smaller than products that use a conventional emulsion system. Smaller droplets give better coverage and lower risk of phytotoxicity. TriTek is also approved for organic use. A 2% rate of TriTek will help reduce overwintering populations of scales and mite eggs while having minimal effects on beneficial populations that are inactive this time of year. Mixing TriTek with another worm material like spinosad or diflubenzuron, can be a good control strategy for peach twig borer.
Bud development in peaches. Dormant sprays occur between leaf fall and bud swell. Delayed dormant sprays occur between bud swell and green tip (UC IPM).