Asparagus Ferns Need Fungicide Protection

desert ferns

Asparagus Ferns

Asparagus is a perennial crop that should have a productive life of 15 or more years. Asparagus spears grow upward through the soil from underground crowns. The spears are cut by hand every 2-5 days. After two to three months, spear harvest ceases and the spears are allowed to grow into ferns with a thick canopy of feathery leaves. During the fern stage, the plant produces and stores energy for the following year’s crop. Purple spot on asparagus was first reported in the U. S. in 1981. The main damage from purple spot is on fern growth. Fungal damage to the ferns results in defoliation of the needles which reduces the flow of carbohydrates to the roots and lowers next years yield.

“Purple spot of asparagus is an important fungal disease in many growing regions including Michigan, California, Washington, England, and New Zealand. The fungus overwinters as pseudothecia on the surface of asparagus fern debris and releases ascospores as primary inoculum in the spring.

Purplish lesions may subsequently develop on the spears, making them commercially unacceptable, especially for the fresh market… Following infection, tan to brown lesions may develop on the fern and premature defoliation may occur. Premature defoliation of the fern limits its photosynthetic ability, resulting in decreased carbohydrate reserves for the crown that may negatively affect yields in the following years.

Growers apply fungicides to manage purple spot on the fern after the last spears are harvested; fungicides are not applied to asparagus spears that will be harvested.”

Authors: Granke, L. L., and M. K. Hausbeck.
Affiliation: Department of Plant Pathology, Michigan State University
Title: Influence of Environment on Airborne Spore Concentrations and Severity of Asparagus Purple Spot.
Source: Plant Disease. 2010. 94[7]:843-850.

100 years of Fungicide Protection Against Brown Rot of Stone Fruit

Brown Rot on Peach

Brown Rot on Peach

The brown rot fungus infects all the acres of cherries, peaches and nectarines in the U. S. Ash-gray masses of millions of spores appear on the fruit and the fruit becomes completely rotten and soft within a few days. Brown rot caused substantial fruit losses before the development of fungicides. Most peach growers expected to lose 50-75% of their crop. With the development of a finely-powdered sulfur fungicide about 1912, stone fruit growers began widespread spraying to control brown rot. This spraying has continued to this day.

“Who does not love the delicious taste of fresh peaches, nectarines, plums, apricots, or cherries? Because of their popularity, stone fruits are grown all over the world, but it is not only consumers who like these tasty fruits. Some fungi have specialized in infecting and colonizing stone fruits wherever they are grown. 

There are ways to reduce disease pressure in commercial orchards, including the removal of fruit mummies from the tree canopy, pruning out cankers and removal of wild plums surrounding orchards. However, these measures do not prevent brown rot disease, and growers are still dependent on the application of fungicides for blossom blight and pre- and postharvest disease management.”

Authors: Schnabel, G., et al.
Affiliation: Clemson University.
Title: Sustainable brown rot management of peaches in the southeastern United States.
Source: Outlooks on Pest Management. 2010. October. Pgs. 208-211.

Michigan Tart Cherry Orchards Rely On Fungicide Protection Every Year

Cherry Leaf Spot Infection

Cherry Leaf Spot Infection

Michigan is the leading producer of tart cherries in the United States, with annual yields of 90.9-127.3 million kg, which represents approximately 75% of the total US production.

Leaf spot is the most important fungal disease of cherry trees in Michigan. The appearance of numerous spots on the leaf is usually followed by rapid yellowing and dropping. In experiments, it has been demonstrated that poor control of leaf spot can result in 72% of the tree branches dying during the winter months.

“Cherry leaf spot (CLS) is the most damaging pathogen of tart (sour) cherry trees. All commercial tart cherry cultivars grown in the Great Lakes region of the United States are susceptible to CLS, including the widely grown cultivar Montmorency, which accounts for more than 90% of the tart cherry acreage in Michigan. Left unmanaged, CLS infection causes significant defoliation by mid-summer, resulting in fruit that is unevenly ripened, soft, poorly colored and low in soluble solids. Early defoliation also delays acclimation of fruit buds and wood to cold temperatures in the fall, increases tree mortality during severe winters and reduces fruit bud survival and fruit set the following year.

The almost complete reliance of the tart cherry industry on the cultivar Montmorency has driven a strict dependence on fungicides for disease management. Typically, 6-8 fungicide applications per year are required, beginning at petal fall and continuing through to late summer after harvest.”

Author: Proffer, T. J., et al.
Affiliation: Michigan State University
Title: Evaluation of dodine, fluopyram and penthiopyrad for the management of leaf spot and powdery mildew of tart cherry, and fungicide sensitivity screening of Michigan populations of Blumeriella jaapii.
Source: Pest Management Science. 2013. 69:747-754.

Fly Eggs in Fruit? Insecticides Are the Only Option


Serrated Egg Layer Drosophila


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:,1T79M,6LPYOS,6H5RF,1

Zero Tolerance for Maggots in Cherries Means Growers Must Spray

Cherry Maggot

Cherry Maggot

Pairs of cherry fruit flies have been observed copulating for 18 hours at a time. Each female may deposit 100 to 300 eggs under the fruit skin over a period of thirty days. Eggs hatch in 3-7 days and young maggots feed on cherry flesh, mainly around the pit. Maggots and their frass within the fruit render the product unsalable.

“Insecticides continue to be vital in efforts to control the western cherry fruit fly, the most serious insect pest of commercial sweet and sour cherries in the western United States. … The zero tolerance for fly larvae in cherries has necessitated the use of these highly toxic insecticides in commercial orchards. Isolated homeowner or abandoned trees can be heavily infested and also need to be treated with these insecticides to reduce chances of flies dispersing to commercial orchards.”

Authors: W.L. Yee1 and D.G. Alston2
Affiliation: 1USDA-ARS, Yakima Agricultural Research Laboratory, Wapato, WA; 2Department of Biology, Utah State University, Logan, UT
Title: Effects of spinosad, spinosad bait, and chloronicotiny insecticides on mortality and control of adult and larval western cherry fruit fly (Diptera: Tephritidae).
Publication: Journal of Economic Entomology. 2006. 99(5):1722-1732.