Protect Walnut Crops from the Damage Cause by Sunburn and Heat Stress
Protect Your Walnut Crop From the Damage Caused by Sunburn and Heat Stress
Surround® is a well-known tool for reducing sunburn damage in walnuts. It also can significantly reduce heat stress which can inflict financial losses that frequently go unseen by growers. SURROUND is specially formulated to reflect harmful infrared and ultraviolet radiation away from plant surfaces while allowing the penetration of beneficial Photosynthetically Active Radiation (PAR). SURROUND-treated trees are typically several degrees cooler than untreated trees, and a cooler tree leads to: 1) reduced heat stress, 2) increased photosynthesis and improved plant vigor, and 3) potentially higher yields. And, SURROUND does not block leaf stomata so gases (O2 and CO2) and water vapor continue to move in and out of the plant, maintaining the plant’s natural photosynthetic and cooling processes.
SURROUND reduced sunburn damage 83% and significantly increased walnut kernel quality.
Recommendations for Walnuts
Volume: For 20-foot trees use 200 gallons per acre. Large trees require up to 300 gallons per acre.
Concentration: Use 25 to 50 pounds per 100 gallons of water.
|Problem||Pounds / Acre||Application Instruction|
|Sunburn and heat stress||50-75||Apply to sunburn-prone trees before conditions leading to sunburn occur. Provide thorough coverage with one to two full rate applications 7 days apart. Depending upon the length of the high heat period, three to four applications in total often are needed. Good coverage on small to medium size trees is best achieved at rates of 75 pounds in 100 to 200 gallons per acre to achieve near-drip coverage. Make subsequent applications at half to full rates to maintain even coverage throughout the high heat period.|
- Apply SURROUND to near-drip. Avoid foliage run-off.
- Change travel direction on alternate applications to achieve best coverage.
- SURROUND can be tank mixed with most pesticides. When tank-mixing, always add SURROUND to the tank first. A premix tank is suggested for sprayers without mechanical agitation.
- Use 25–35 pounds of SURROUND in 25–35 gallons of water per acre.
- SURROUND may be applied using standard aerial application nozzles.
- Make applications not more than 10 feet above the top of the largest tree unless a greater height is required for aircraft safety.
- When spraying at low relative humidity, increase droplet size to compensate for evaporation.
A protective film of SURROUND reduces the temperature of sun-exposed walnuts.
SURROUND Effects on Sunburned Walnuts and Quality in ‘Payne’ Walnuts D Hicks, D Hulst; California, 2004