Spring is in the air! With that in mind, let’s stay ahead of issues that can pop up while we come out of hibernation. A few simple sprays early in the season can keep you out of trouble. Horticultural oils and fixed copper sprays are industry standards that provide great benefits for the dollar. Dormant sprays will be kicking off the season, let’s review some of the key points of this timing.
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 the hibernacula is effective at either timing with the appropriate insecticide. European red mites (eggs), two spotted spider mites and obliquebanded leafroller larvae are best controlled using delayed-dormant timing.
Other benefits of a dormant oil spray are;
· 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.
Horticultural spray oils have been in use for over a hundred years. They are a unique tool in our arsenal from the perspective that no pest species have ever developed resistance to them. Brought down to simplest terms, the results one will obtain with oil sprays are governed by three basic factors:
1) the oil and rate used
2) how well it is applied
3) when it is applied
MATERIAL - COVERAGE – TIMING
Oil covers insects with a suffocating film that kills both larva and eggs by a physical interference with the normal gaseous exchange. Coverage is essential! As eggs get closer to hatching, they become more susceptible to being killed with oil. Research shows that oil sprays applied at the beginning of hatch using a lower percentage of oil concentration are as effective as earlier applications at a higher rate. Timing is essential!
So what’s the point? We need to know what our target is and when it’s most vulnerable. Whether it’s green peach aphid, European red mite or pear psylla, missing the optimum timing by a week can make a significant difference in control.
Every spring the question is raised regarding, “How cold is too cold to spray dormant oil?” The text book answer is 45ºF. A bit of common sense also figures in. Is the temperature on the rise, or decline? Is it windy, damp, cloudy, etc.? Pay attention to freezing temps during the 48 hour period before application and for 24-48 hours after. If present or predicted, hold off. Having said that, keep in mind where we farm. Most years you will need to pick the “least bad day” to spray. I’ve never seen plant damage from spraying oil when it is too cold, but I have seen pest damage when a grower missed an application while waiting for that perfect day.
It's common to make an application with a tank mix of several different materials and formulations. There's a specific mixing order that will help keep you out of compatibility problems. In other words, spending the rest of your day cleaning out your sprayer!
1) soluble packets
2) wettable powders, or water dispersible granules,
4) emulsifiable concentrates,
5) oils. Always, always, always add oils LAST!
Before this growing season gets rolling, take a moment to review the last one. How was your crop? If you had pest or quality issues, now is the time to put a plan together to avoid the same problem this year. We are here to help! Please give us a call if you want to discuss a program.
“The farmer has to be an optimist or he wouldn’t still be a farmer.”