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Organic blueberries

at Grindstone farm

by Richard de Graff, V Ladd de Graff, Nancy Simcox & Ann McMahon

Nestled 5 miles east of Lake Ontario, near the small rural community of Pulaski, New York, lies the Grindstone Farm organic blueberry patch. This blueberry patch is approximately 5 acres in size, surrounded by pines and deciduous trees along with a naturally spring fed pond. The soil is predominantly sandy with a natural pH of 4.5.

Because wild blueberries thrived in this area in the 1950's, the decision was made to establish a commercial plantation. Unfortunately, the different varieties are unknown to us at this time. Throughout the past 10 years, we have employed several strategies for improving the condition of our blueberry crop. These include pruning practices, pest control methods and fertility. Depending on the area in which you are located, these methods may or may not work for you.

When the farm was bought in 1980 a well established planting of blueberries existed; however the patch was overgrown in size as well as crowded by other undesirable trees and weeds. Due to neglect over the years, ladders were needed to pick the fruit off the top of the bush. Our approach to reclaiming our plantation was to cut the blueberries off with a bushhog, although it could also be accomplished at ground level with a chain saw. This sacrifices the first year's fruit, but it is necessary for a healthy plant the second season.

The blueberry season begins for us in early March. It is essential that pruning take place at this time for the removal of all the dead wood or anything that shows winter injury or frost damage. In fact, pruning can get underway when there is still snow on the ground. We look forward to completing this task during those brisk days before black fly season sets in. To stimulate new growth approximately one third of the oldest dead wood is cleared. Blueberries fruit on two year old wood therefore there is no need to have any wood or branches older than five or six years on your bush. This technique has proven to be one of the most effective ways to increase the size and yield of our blueberry crop. We use pneumatic pruners because of their speed leverage, and sturdiness. An alternative tool is hand loppers with high leverage.

Following pruning, it is important to pile the wood away from the plantation and burn it so as to prevent the spread of disease. Diseases such as mummyberry, phomopsis and botrytis can infect an entire field.

The blueberries are planted in rows eight feet apart. We have grasses growing between our rows, which we keep mowed off until the berries start to ripen. At this time we cannot mow because the branches hang down into the row, making it impossible to drive the tractor through without damaging the bush and knocking off the blueberries. Therefore, we recommend al least a ten foot spacing for new blueberry plantings.

The pest control methods are initiated around bud break, which in our area is the middle to the end of April. It is when the buds swell and before they actually come out and open up that the bushes are sprayed with lime sulfur. Lime sulfur, a dormant spray, is used to control botrytis, which is a mold. This is a preventative measure to avoid mold spores from multiplying in cold, damp weather during blossom. These molds can inundate an entire field. The result of molds is that it causes the blossoms to turn brown and die. We have used lime sulfur with success, and we have not had a problem with this mold since the applications. It is a devastating feeling for a farmer to look at an entire crop of dead blossoms while . the rain continues falling.

In the beginning to the middle of May we release Trichogramma wasps at the rate of approximately 60,000 per acre of fruits This is to control cranberry fruitworm which was identified through insect monitoring in 1989. The cranberry fruitworm is a lepidoptera moth which lays its egg at blossom amp. The egg hatches as a worm which bores into one berry and expands in size, climbs out of that berry and into the next Each time it moves it clusters the berries together, thereby rendering an entire cluster of berries unharvestable. Then the worm drops to the ground and pupates to start the cycle the next year. We feel that the Trichogramma wasp helps to control the cranberry fruitworm. We have not had 100 percent control in the past two years that we have used them, but feel that we have made advances while continuing to research other methods. Other controls would be Sabadilla and Ryania or rotenone sprays. We have avoided them because of the expense involved. This is the only insect problem that we have, however this year there is some blueberry maggot problem, which we have not previously experienced. Controls for this pest include Rotenone Dust. It can be monitored with yellow sticky traps. The maggot fly looks like a house fly with black stripes on its wings.

During blossom the field is sprayed with a sugar and seaweed mix (Maxicrop). The sugar and the seaweed help the plant to get through the stress of blossom, and a side effect is that it also stimulates the bees to work in the blossoms. More bees work in the blueberries after being sprayed with sugar. This is the only treatment to the blueberries until harvest.

At Grindstone Farm we feel the blueberries are best marketed on a U-Pick basis. Some years we have more berries than U-Pick customers, so we also pick for fresh market and ship berries UPS direct to the consumer. The picked berries are basically charged the same as U-Pick plus the expense of harvesting labor and shipping. For the berries that we wholesale, we package them into 12 pint flats. Each pint is covered with a special cellophane wrapper which helps to retain freshness, and each one has a product label included in it identifying that it meets the market standards. Much labor is involved in picking; it is a very time consuming task. This is something for anyone who is going to be planting blueberries to consider - where will your labor pool come from to harvest the crop? One of the advantages of blueberries is that when they are ready, they don't have to be picked on that day, they can be picked within the next couple days. The detriment to waiting is birds.

Birds can be devastating to a crop of blueberries, especially bluejays, robins, and redwing blackbirds. We use bird scare-eyes and a sound Avalarm. On occasion we have been known to walk through with a gun doing some shooting. The best control we know of is to have an abundance of people in the field picking the fruit before the birds have an opportunity to get them!

After all of the blueberries are harvested, and while labor is still available, we go through and clear out all of the invasive brush, bramble, small trees or diseased branches which have grown during the season. These are discarded away from the field and burned. The time frame for this would be late August or early September, preferably before frost. The reason for this is to prevent the undesirable plants from surviving the winter. After that we go through and add any soil amendments that our summer soil tests or leaf analysis tell us we should add. Ideally we would also mulch the plants with old hay, straw, wood chips or saw dust at this lime. Now with these management strategies in place we look forward to a mild winter with abundant snow to blanket and protect our next year's blueberry crop.

Copyright 1991 The Natural Farmer. All rights reserved.


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