Turkey Ridge Orchard is a family owned, 140 acre certified organic apple orchard. We produce apples and process apple cider for wholesale markets in Wisconsin, Minnesota, Illinois and Iowa.
We were assisted in the project by George Siemon, a local chicken grower. George operates on organic dairy farm and raises chickens for a direct consumer market.
John Aue, an orchard entomologist helped with the detection of Plum Curculio and did late season fruit assessments.
PROJECT DESCRIPTION AND RESULTS
1) Early detection of Plum Curculio
Goal: Using sticky traps of various shapes, sizes, and scents attempt to trap the plum curculio when they first arrive in the orchard from the surrounding woods.
Background: Plum Curculio can be devastating to an orchard. Left unattended Plum Curculio can damage 50-90% of the fruit. The female Plum Curculio spends 10-14 days mating prior to beginning her oviposition on the fruit. Plum Curculio appearance is most often detected by looking for damaged fruit. We wanted to find a way to attract the Plum Curculio to a trap during the mating stage prior to the commencement of fruit damage. Once the female begins to oviposit she will lay over 500 eggs in her life cycle, generally with only one egg in each apple. The female will move from apple to apple, tree to tree until she is done with her egg laying cycle.
Methods: White traps coated with tanglefoot were placed in areas of previous years damage. Some traps had apple essence scent on a sponge glued to the traps. Our most creative trap was a tubular cricket cage coated with tanglefoot. Live plum curculio were placed inside the cricket cage. Two plum curculio were caught on a cricket style trap.
Results: Two plum curculio were caught in a cricket style trap. One was caught on a white 8 ½ x 11” tag board sheet on May 21st. this was the first plum curculio observed for the year. This was the only plum curculio observed on any of the white traps during the rest of the year.
Conclusion: The traps were not as effective as using a bang board for early detection. However, the daily monitoring near the trap areas and subsequent hunting in the orchard provided some excellent observations.
1) Plum Curculio will mate in the trees
2) A majority of the Plum Curculio prefer to over winter on a southern exposure.
3) Plum Curculio start at the bottom of the hill and move towards the top and over to the other side of the hill searching for trees with a fruit sent.
4) Plum Curculio seemed to move along the edges of a drive row as they worked towards the top of the hill.
5) Plum Curculio will be found first in trees with the earliest fruit set.
6) Plum Curculio seem attracted to the tallest trees in the row.
7) Plum Curculio will emerge from the woods based on the warming of the soil not air temperature.
2) Use of range chickens to reduce Plum Curculio damage
Goal: Experiment with range chickens to determine if they can reduce Plum Curculio damage and be profitably raised.
Background: Experiments at Rodale Institute, Michigan State University and advice from Stuart Hill of McGill University suggest that range chickens will suppress the Plum Curculio population in an orchard. It is theorized that chickens are audibly attracted to the sound that mating Plum Curculio make. It is also theorized that Plum Curculio spend significant amount of time on the ground while they are mating.
Methods: On May 9th and May 19th a total of 1084 five to six week old mixed run chickens were acquired from a local grower. The chickens were chosen for their future marketability as fryers or egg layers. The varieties were 60% Black Austolop, 30% Hampshires, and 10% Barred Rock. Two 8’x10’ portable chicken houses were built by students at North Crawford High School. The chickens were divided among the two houses and each house was placed in a known point of Plum Curculio entry based on prior years observations. Chickens were released at 6 am and placed back in their houses by 9 pm. The chickens were fed and watered each day. Feed rations were about ½ of the rations used by a grower raising chickens in a confined area. The chickens ate insects, grass, weeds, and apples to complete their diet. Using the weed badger we periodically tilled the soil under the tree line to give the chickens fresh dirt to scratch on. During the period of Plum Curculio activity each chicken house was moved periodically inside a 2-3 acre circle. By July 8th 450 roosters (or what we thought were roosters) were sold back to the local grower. By August 13th 260 pullets were sold to a local farmer who was part of an organic egg production pool. By September 5th all of the remaining chickens (69) were sold to local people.
Conclusion: 1) Numerical results on Plum Curculio control means that chickens don’t eliminate Plum Curculio but still may suppress the population. On June 5th Kay Johnson noted that in areas where the chickens ranged when the Plum Curculio first came into the orchard the populatin was less than surrounding areas. From this you might surmise that the chickens are most effective when the Plum Curculio first come in the orchard and is spending time on the ground mating. When the mating process is ended and the Plum Curculio are in the trees the effectiveness of the chickens decreased.
2) Chickens love to scratch in freshly turned dirt. Plum Curculio pupae are in the soil about 22 days after an egg is laid. We do not have nay idea what the impact of the chickens would be on the pupae in the soil
3) It would be more cost effective to hire high school students to hunt Plum Curculio than to manage the chickens.
4) Coyotes and hawks like chickens and are very adept at catching them during daylight hours.
5) If we did use chickens again we would have 20 cages with 50 chickens per cage. Cages would be placed in all areas of the field. This would vastly increase the area covered. In our system hundreds of chickens tended to bunch up together around the house. We would be around the chickens every day. This would deter daylight predators.
We went and got the chickens (541) on May 9. Arriving back at the orchard we put them in the coop built by the Vo-Ag class at school. Early the next morning we pulled the coop out on the Jake to Block 11. They were in about the center of the block. It was hoped that they would range far enough to cover both the top and bottom of the block.
The weather is cool and rainy. I’m afraid the chickens are too small to be very effective in hunting Plum Curculio because they don’t range far enough away from the coop to cover a very large area.
The chickens tended to range only in the direction that the door of the coop faced. Therefore we cut a door in the other side of the coop. we moved the coop about every 5 days as the chickens gleaned every blade of grass in the area and it was very difficult to get around to feed and water them. At first they didn’t require much feed, but as they grew so did their appetites and range area. We decided that about 25-50 chickens in an area would have been enough and should have had several smaller coops that could have been moved more easily to the areas where the Plum Curculio were active as determined by our hunting.
The first coop of chickens were active, the red ones more apt to range farther than the others. Feed has increased from 25# to 50# in about 1 week. Sam shot at a coyote that was on the edge of the orchard. The hawks are there every day, soaring and looking things over. How many will they get? We tilled the rows around the coop to make more bare ground by the trees for them to scratch and hunt.
The second group arrived on the 19th. They were much smaller and the mortality rate was 4 times that of the other group which was about 2 weeks older when we put them out in the orchard to range. This was perhaps because of the colder temperatures which caused them to huddle and smother. This group was put on the other side of the hill in block 5.
By the 25th it took 100# of feed each day. Waterers were rinsed and filled 2x each day. We mowed regularly and tilled to encourage scratching for bugs. Some more predators showed up by the coops. A mink was under one with a chicken it had killed and was feeding on. One morning the screen on one of the coops was half ripped off. Tracks in the mud identified raccoon, coyote, mink and even wild turkeys had been around the coops. If we decide to continue with the coops it will be a full time job for one person to keep them cleaned, moved and cared for.
When the Plum Curculio count was down and from initial observations, damage was less where the coops had been early. This was perhaps when the Plum Curculio were mating on the ground. However, some of the Plum Curculio was found mating in the trees, so control was not as good as expected.
Also, because of the rain and muddy conditions, we were not able to move the coops as often as we would have liked. One problem that we noted was that the chickens had a real liking for the apples and would fly up and roost in the trees to get at them. Some of the trees were completely defoliated by the chickens up as far as 2-3 feet. Some of the low apples had been pecked and were on the ground.
The question is whether the chickens were efficient enough considering the labor and cost or would it have been better to hire 4 more bug hunters for a 6 week period? Will we be able to bang the bugs out when the trees are bigger? Is there another alternative?
A field day was held on October 17th, 1993 to explain and demonstrate the project. Over 60 people attended from three states. We are on agenda to give a slide presentation about the project at the 1994 Upper Midwest Organic Conference.