jan-feb-2021

Weed control in young orchards is a particular challenge due to the “excellent” weed growing conditions in very young orchards (lots of light, water and nutrients). There are only a handful of pre-emergent herbicides labeled for use in first leaf orchards. Trellis ® , Goal ® , and pendimethalin (Prowl ® , etc.) are three that come to mind, but check with your PCA about all options. The chapter “Weed Management in Young Orchards” in UC ANR’s “Young Orchard Handbook” (developed by UCCE Orchard Advisor Kat Jarvis-Shean) has great information on weed management. Good weed control in young orchards also helps with rodent control, especially voles (also known as meadow mice). Rodent Control Now is a good time to control gophers. Use two separate management practices in parallel to get the best control. Trapping is time consuming but effective, especially if the trappers are experienced or have some training before starting to work. If you have had enough rain to seal soil cracks, fumigation with aluminum phosphide tabs is effective in winter. Check with your ag commissioner to make sure applicators meet all requirements and follow all regulations when using this restricted material. February is an excellent time to control ground squirrels. Pollination A large crop at harvest requires good nut set and that requires good bee activity in the orchard at bloom. The current UC general recommendation for bee hive stocking rates is one to three strong hives per acre. A strong hive contains at least eight frames covered with bees, an actively laying queen, and one to two frames of brood. Where cold, rainy and/or windy conditions limit bee flight (recall the 201 9 bloom), two to three strong hives may be needed to supply enough bees to set a decent crop when there are only narrow windows of good bee weather. Good bee weather is at least 59 degrees Fahrenheit, no rain and less than 1 0 miles per hour wind speed. There is a direct relationship between active frames of bees in a hive and the amount of pollen returned to the hive. More frames covered with bees and several frames of brood in a hive means more foraging bees and more flowers pollinated, a lot more. The best possible start to the season begins with strong hives in the orchard at the start of bloom. Pollination contracts should include language stating hive strength and that some fraction of the hives will be inspected at or soon after delivery to confirm that the contracted hive strength is delivered. The hive strength check should happen at or close to delivery. Almond flowers are an excellent food source for honey bees and a four-frame hive at hive delivery can be much stronger close to hive release. Growers lowering bee stocking rates in an effort to save money are the most in need of contract language stating hive strength and a hive inspection. A single eight-frame hive collects two and a half times the pollen as a four- frame hive. Hives should be placed in locations where early morning sun will warm the hives and in groups in the orchard no more than a quarter of a mile apart. Even though bees will fly three miles for food or water, they will usually stay within a few hundred yards of the hive if food and water are close to the hive. Bees need water and will go find it (somewhere else) if not available in your orchard. Check-in with your beekeeper to agree who provides the watering stations for bees in your orchard. The water stations should be covered or moved and the water changed after spraying. Bees can’t drink while flying and will drown trying to get to water if there is no landing site at the water source. A five-gallon bucket with clean water and an old towel or piece of burlap draped over the bucket lip and into the water works as a bee watering site. Bees can be harmed by pesticides. Certain pesticides and practices can be particularly harmful. In particular, all insecticides (except B.t. products such as Dipel) should be 4 9 J A N U A R Y – F E B R U A R Y 2 0 2 1