Surprise! Your Strawberries are Moldy

Grey mold on strawberries

Gray mold on strawberries

Consumers sometimes buy picture-perfect strawberries only to find them covered in mold after a few days. The cause: the gray mold fungus which infects the berries in the field but which remains symptomless until the fruit ripens. The fungus produces a velvety gray growth on the surface of the berry. Gray mold spreads in shipping containers when the fungus grows from a rotting berry to an adjacent healthy fruit. 100% of US strawberry acres are estimated to be infected with the gray mold fungus. Widespread infections are prevented with fungicide treatments.

“Gray mold is one of the most economically important diseases of cultivated strawberry (Fragaria × ananassa), and a significant threat to the United States’ $2.4 billion strawberry crop… Crop losses resulting from gray mold disease are especially severe under moist weather conditions, and occur not only during the crop growing season but also after harvest and during storage and transit.

The control of gray mold in commercial strawberry fields is largely dependent on the application of fungicides during bloom and fruit maturation.”

Authors: Grabke, A., et al.
Affiliation: Clemson University.
Title: Fenhexamid resistance in Botrytis cinerea from strawberry fields in the Carolinas is associated with four target gene mutations.
Source: Plant Disease. 2013. 97[2]:271-276.

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Organic Berry Production in Europe is at a Dead End

Damage from Raspberry Beetle

Damage from Raspberry Beetle

The growing of organic strawberries and raspberries in Europe has not expanded in the past decade. There is organic production in most countries, but it is on a very small scale. Organic berry production in Europe is likely to remain a niche market largely due to lack of control of very damaging insect pests.

“Many European growers of organic strawberry and raspberry have large losses in yield (sometimes >80%) and reduced quality of their products because of insect damage. Among the major threats are the strawberry blossom weevil, the European tarnished plant bug and the raspberry beetle. In organic soft fruit production there are no effective control measures for these pest insects.”

Authors: Wibe, A., et al.
Affiliations: Bioforsk Organic Food and Farming, Norway.
Title: Management of strawberry blossom weevil and European tarnished plant bug in organic strawberry and raspberry using semiochemical traps – “Softpest Multitrap”
Source: NJF Report. 2013. 9[8]:31.

Strawberry Fields Forever? Thanks to Fungicides

Strawberry Yields: UK

Strawberry Yields: UK

Strawberry cultivation in the UK reached 13000 hectares by 1924. While the area today is just one-third of the 1924 area, strawberry production has more than doubled due to yield per hectare increasing 5-6 fold. A major factor in increased strawberry yields in the UK has been the increased use and variety of fungicides used.

“The second productivist practice was the increased use of plant protection products from the 1960s. In 1965, up to 11% of the strawberry crops were not sprayed with pesticides; this figure had decreased to less than 2% by 2006. The spray area for fungicides also increased, from 6058 ha in 1965 to 45,960 ha in 2006. This is higher than the area of land cultivated for strawberries since it takes into account multiple sprays per season. The increased use of pesticides during this phase contributed to increasing yields, by decreasing disease pressure. This also had an impact on reducing yearly variations in yield, as pesticides enabled growers to reduce the impact of weather on their crop by reducing disease incidence.”

Authors: Calleja, E. J., et al.
Affiliation: University of Warwick, UK.
Title: Agricultural change and the rise of the British strawberry industry, 1920-2009.
Source: Journal of Rural Studies. 2012. 28:603-611.

A Longer Strawberry Season in Canada Would Require More Fungicide Sprays

Anthracnose fruit rot

Anthracnose fruit rot

Ripening strawberries are very susceptible to anthracnose. The pathogen spreads rapidly through fruiting fields during rainy, warm harvest seasons and can quickly destroy a crop. Light-brown water-soaked spots form on ripening fruit and rapidly develop into firm round lesions followed by the eruption of pink spore masses in a slimy sticky matrix which are dispersed by splashing or wind-driven rain.

“In Canada, strawberry is cultivated mainly in Quebec, Ontario, British Columbia and the Atlantic provinces. Ontario ranks as the second highest strawberry producer (30%) in the country, with a farm-gate value of Cdn$ 20.8 million. Most of the fruit produced in Canada are from June-bearing cultivars, with a season that usually spans 5-6 weeks in June and July. In the off-season, large quantities of strawberries are imported, which were five times higher in 2011 than in 2003. The Canadian strawberry industry has given high priority to cultivation of day-neutral strawberry to become more competitive with the import market and increase the availability of fresh Canadian-grown strawberries to 4-5 months.

Anthracnose fruit rot (AFR), caused by Colletotrichum acutatum Simmonds, is one of the major diseases affecting yield in Ontario and other provinces. Pre- and post-harvest fruit rots caused by the fungus reduce marketable yields and the marketability of fruit, respectively. Long wet periods and warm temperatures (20-25 °C) during flowering and fruit development are favourable conditions for development of anthracnose fruit rot.

With the increase in production of day-neutral cultivars in Canada, attention should be given to the differences in cultivation practices from June-bearing cultivars. Since day-neutral strawberry have a longer cycle of fruit production, the risk of diseases and pests is also higher and thus different management strategies are required.

Since the day-neutral cultivars can be grown for a long season (4-5 months), numerous sprays (8-10) of fungicides are required to control diseases.”

Authors: Burlakoti, R. R., et al.
Affiliation: Weather Innovations Consulting LP.
Title: Evaluation of epidemics and weather-based fungicide application programmes in controlling anthracnose fruit rot of day-neutral strawberry in outdoor field and protected cultivation systems.
Source: Canadian Journal of Plant Pathology. 2014. 36[1]:64-72.

Fly Eggs in Fruit? Insecticides Are the Only Option

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Serrated Egg Layer Drosophila

berries

Blueberries: Drosophila Infestation (Right)

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.”

Author: Nancy Bean Foster
Affiliation: Union Leader Correspondent
Title: Fruit farmers on guard for new pest
Source: Union Leader. August 26, 2013. Available at: http://www.unionleader.com/article/20130827/NEWHAMPSHIRE07/130829419?dm_i=1ANQ,1T79M,6LPYOS,6H5RF,1

To Remain Viable, California Strawberry Growers will need to use Fumigants for Years to Come

Strawberry Production: California

Strawberry Production: California

California is the top strawberry growing state producing 2-3 billion pounds per year. California accounts for 20% of the world’s production of strawberries. Since about 1965, approximately 90% of strawberry land in California has been fumigated before each crop is planted. Statewide average strawberry yields tripled following the adoption of fumigation. Generally, the increase in strawberry yield is credited to effective control of the soilborne fungal disease, verticillium wilt, which attacks the water-conducting tissue of the plant. In recent years, the use of fumigants in California has been under intense regulatory review with a phaseout of methyl bromide and use restrictions which could include expanded buffer zones in strawberry fields where fumigation will not be permitted. A recent working group in California assessed the status of nonfumigant alternatives……

“Owing to potentially devastating soilborne pests, strawberry growers have relied on soil fumigation treatments for many years.

Director Brian Leahy of the California Department of Pesticide Regulation convened in April 2012 a working group of industry and scientific leaders to develop an action plan of research priorities for developing cost-effective management tools and practices for soilborne pests of strawberries in the absence of conventional fumigants.

The Working Group recognized that over the last 20 years, many studies focused on breeding disease-resistant plants and testing soil treatments such as anaerobic soil disinfestation, biopesticides, biofumigants, soilless substrate, steam, and solarization.

Yet to be done is testing combinations of alternatives in extensive field trials and on-farm demonstrations.

Full implementation of the action plan will require a major commitment of time and resources by a broad range of groups in the private and public sectors, such as researchers, funding institutions, growers, grower organizations, farmworker advocates, community and environmental organizations, and consumers.

Even with full commitment to implement this action plan, the strawberry industry will need to continue its use of fumigants for years to remain viable in California.”

Title: Nonfumigant strawberry production working group action plan
Source: California DPR. April 2013. Available at: http://www.cdpr.ca.gov/docs/pestmgt/strawberry/work_group.htm

Growing Berries in Germany Requires Fungicides to Prevent Mold

Gray Mold

Gray Mold

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.