Orchard Management


Careful pesticide use and proper hivemanagement are among the keys to success.


A


fter winter pruning, which generates a lot of potential for large, quality fruit and better return bloom, the next major effort is up to the pollinating insects. Many of the dynamics of variability are always there – temperature which determines bloom timing and length of the bloom period, which plays havoc with growers’ minds and practices. In addition, pre-bloom and bloom nutrition and moisture availability play their part in the decision-making that takes place.


The pollinating insects are critical to this whole process. Bee numbers, hive strength, timing of placing and location of hives are strong factors in pollination effectiveness.


Over decades, growers have had to be extremely careful with pesticide use during the bloom period. Nothing has changed. Sevin, a good tool for thinning programs, is the one with which problems can arise with bee death if blossoms are open or if bees are active at all in the orchard.


Thirty-plus years ago, grower knowledge of bees and an appreciation of the beekeeping industry had a long way to go.


Difficulties mostly revolved around the bloom period. There was always the tight timing of necessary sprays at pink, when early blossoms might be starting to open, and the complications of late bloom still coming out on the immature flowers that formed on younger wood. This could get especially worrisome when growers needed to get in to the orchard for spraying Sevin – early when fruitlets were very small and or later as they reached around 12 mm or larger in size.


Also, in many of our orchards there are different varieties of apples, with different bloom dates. In the Southern Okanagan there may also be a range of stone fruits with their range of bloom dates. It takes a good effort on the part of growers to manage timing and placement of hives to avoid impacting bees.


By Peter Waterman Nurturing the blooms and the bees In many cases it


means calling the beekeeper and having hives removed.


Education efforts over the intervening time have helped a great deal.


For decades the Okanagan has had


an integrated mite control program and as a result has focused on pesticides that have less or no impact on predacious mites and insects. The balance of the control program has focused on reduced environmental impact.


Our industry has moved away from many harmful materials and has been careful to gradually educate growers on timing and use patterns around periods when bees are active.


In addition to Sevin, our industry does use Admire at petal fall on apples. It is used primarily for leafhoppers, campylomma, and aphids. It is not to be used during bloom and only once per season. This material is one of a group of pesticides called neonicotinoids. These materials are systemic and move readily in the xylem of plants from point of spray contact, as well as soil, into leaves, fruit, flowers, nectar and in the guttation fluid of leaves. According to our Tree Fruit Production Guide it is the only material of its group used close to the bloom period. There are several other neonicotinoids used for summer codling moth control – Calypso 480 SC (thiocloprid) which has a low toxicity to bees but a high toxicity to lacewings, Assail 70 WP (acetamiprid), which is toxic to bees and also controls aphids, leafminer, and leafhoppers.


The third material is called Clutch 50 WDG (clothianidin) but is only listed for suppression of codling moth. Essentially, these materials, when used according to label and production guide recommendations, have little impact on bee health as beekeepers have removed their hives for the summer.


There are several recommendations for uses of some of the neonicotinoids in other tree fruits as well — apricots, cherries and peaches — but all for


summer use except peaches at husk fall, when Admire is recommended for green and black peach aphid. The greatest impact of this group of pesticides has been on many other crops throughout North America. There is a general belief that its use is one of the contributing factors to Colony Collapse Disease, (CCD).


There are other factors contributing to CCD and general hive strength — mites, fungi, and viruses. Hive management, overwintering conditions etc., will make a difference for the pollinating requirements of tree fruit growers in the spring. Keeping and managing a bee colony is complex, and doing it well takes a great deal of experience.


Some knowledge of what a beekeeper has to do may be helpful for growers in order to to understand where they fit into bee survival and hive strength. For ongoing information, refer to the British Columbia Honey Producers website, bcbeekeepers.com — Retired orchardist and


horticulturist Peter Waterman can be reached at peter@omedia.ca


British Columbia FRUIT GROWER • Winter 2013-14 19


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