Four to seven fungicide applications are made per blueberry acre for control of nine diseases of which mummy berry disease is major. The fungus that causes mummy berry overwinters in shriveled mummified blueberry fruit on the ground. In early spring, cup-shaped structures of the fungus grow on mummified berries. Each cup-shaped structure produces an average of 61,000 spores a day for 9 days. Spores infect young developing twigs and flowers. Fungal tissue colonizes the developing berry. Infected berries turn a cream color and begin to dry (mummify); the mummy retains a shape similar to normal fruit and is composed primarily of fungal tissue.
“Mummy berry disease, caused by the fungus Monilinia vaccinii-corymbosi, is a major disease confronting blueberry growers in North America. …Most losses associated with the disease are due to the rejection or downgrading of commercial blueberry shipments that contain mummified fruit.
Management of mummy berry disease requires repeated applications of fungicide from vegetative bud break through the end of bloom in order to mitigate both shoot blight and flower infection.”
Authors: Tarnowski, T. L., A. T. Savelle and H. Scherm. Affiliation: Department of Plant Pathology, University of Georgia Title: Activity of fungicides against Monilinia vaccinii-corymbosi in blueberry flowers treated at different phenological stages. Source: Plant Disease. 2008. 92:961-965.
The invasive spotted wing drosophila fly came into the US from Asia in 2008 and has spread throughout the US. The fly prefers softer, sweeter ripe fruit- cherries, raspberries, blueberries,blackberries and strawberries. The female flies use saw-like blades on their abdomens to cut through the skin of ripe fruit and lay their eggs inside. The eggs hatch into worms that feed on the flesh of the fruit – ruining the fruit for sale. Insecticides are currently the only option for drosophila control and growers throughout the US are being advised to spray.
“The spotted wing drosophila, a tiny fly that can take a big bite of orchards and gardens, has gradually been making its way across the country from the West Coast and has discovered the summer bounty in the Granite State is much to its liking, according to Dr. Alan Eaton, an entomologist with the University of New Hampshire.
If the flies show up around the time the fruit ripens, the farmers have to immediately spray to kill them off, Eaton said. There are both standard and organic remedies available, he said, but spraying is vital to saving crops. “We’ve had a few growers who weren’t listening to us and their entire crops were wiped out,” said Eaton.”
The German population has access to high quality strawberries, blueberries and raspberries that are grown in the country every year. However, the climate in Germany is conducive for the growth of mold in the berry fields making fungicide use necessary.
“Small-fruit production is an important component of Northern German agriculture, covering some 4,000 ha of strawberry, 100 ha of raspberry, and 1,500 ha of highbush blueberry as well as smaller acreages of redcurrant, gooseberry, and blackberry. Under the cool and humid regional climatic conditions, several fungicide treatments at bloom are essential in order to control phytopathogenic fungi, notably the gray mold pathogen Botrytis cinerea.”
Author: R.W.S. Weber
Affiliation: Esteburg Fruit Research and Advisory Center, Jork, Germany
Title: Resistance of Botrytis cinerea to multiple fungicides in Northern German small-fruit production.
Publication: Plant Disease. 2011. 95(10):1263-1269.
Japanese beetles are often present in blueberry fields and are collected along with the berries at harvest. Because of zero consumer tolerance for bugs in blueberry products, insecticides are necessary to remove the beetles from the blueberry fields before harvest.
“The Japanese beetle, Popillia japonica Newman, is an invasive pest of fruit and vegetable crops, turfgrass, and ornamentals in eastern and central North America. … During the adult emergence period of June to September in Michigan beetles can be observed feeding and mating in clusters on host plants.”
“Much of the food industry maintains a zero tolerance standard for insect contamination at pack-out, which places added pressure on growers of fruit crops such as cherry, peach, plum, and blueberry that may be harvested when beetles are present. The majority of commercial blueberry producers use over-the-row mechanical harvesters for collecting fruit from their fields. This harvesting method does not effectively discriminate between beetles and berries, so adult Japanese beetles are a significant contamination risk in fields being harvested where Japanese beetle has not been controlled.”
“Color sorting technology has been adopted by many large processors to detect and remove beetles, providing >95% removal. Even with these management components available to help minimize the risk of fruit contamination with adult beetles, conventional insecticides remain the primary approach to in-field management of Japanese beetles in fruit crops.”
Authors: J. Wise¹, C. Vandervoort² and R. Isaacs¹.
Affiliation: ¹Department of Entomology, Michigan State University; ²Pesticide Analytical Laboratory, Michigan State University.
Title: Lethal and sublethal activities in imidacloprid contribute to control of adult Japanese beetle in blueberries.
Publication: Journal of Economic Entomology. 2007. 100(5):1596-1603.
The New York Times ran an article with this title in 2011 to inform readers why there are so few organic blueberries grown in New Jersey – “the blueberry capital of the world”. It seems that the organic blueberry growers are powerless to prevent massive feeding on their berries by insects that call New Jersey home. On the other hand, blueberry growers who use chemical insecticides are able to control the insect problem and harvest 2 to 4 times more blueberries per acre.
“New Jersey is one of the country’s top producers of blueberries, yet only a small number of farms are organic. And considering all the obstacles presented by nature, it’s not hard to see why. Insects like the root grub and the plum curculio, as well as some fungi, contribute to organic farmers’ loss of up to 50 percent of their berries a season, whereas conventional farmers may lose 5 percent or 6 percent, said Peter Oudemans, a Rutgers professor and a plant pathologist at the Philip E. Marucci Center for Blueberry and Cranberry Research in Chatsworth, Burlington County. Blueberry plants are native to New Jersey, Dr. Oudemans said, which makes them a natural food choice for native insects. ‘Planting a solid acre of organic blueberries in New Jersey is like throwing a peanut butter sandwich into a room full of kindergartners,’ said Dr. Oudemans, of Hammonton, ‘the blueberry capitol of the world,’ according to a local highway sign. ‘Everything around is going to go for them.'”
“‘We have to do twice the work of conventional growers,’ Mr. Condo [an organic grower] said. ‘It’s a lot harder and much more labor-intensive. Conventional farmers probably get around two or three thousand crates per acre. We’re lucky if we get 700 to 900.'”
Authors: Tammy La Gorce
Title: Organic blueberries don’t come easily.
Publication: The New York Times. June 17, 2011.