Increased Insecticide Use Protects Onions from Viral Infections

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Onions infected with iris yellow spot virus

Iris Yellow Spot Virus (IYSV) was first discovered in the U.S.in 1989 infecting onions in the Treasure Valley of Idaho and Oregon. IYSV typically does not kill plants; however the virus reduces plant vigor and bulb size. Once plants are infected with IYSV, there is no cure. The virus is transmitted to onions by the feeding of an insect: onion thrips. The disease spreads rapidly in fields with large numbers of thrips. Losses up to 100% have been reported. Onion thrips populations are reduced by the application of insecticides in onion fields thus preventing transmission of the disease to onion plants.

Iris yellow spot virus pressure in this region has not been nearly as bad as it was last year, when it wiped out some onion fields. “The virus seems to have been held off well this year,” said Paul Skeen, who farms near Nyssa, Ore. Farmers in the Treasure Valley area of southwestern Idaho and eastern Oregon produce about 25 percent of the nation’s bulb onions and the virus is one of their main production challenges. It weakens the plant and reduces onion production. It can substantially reduce onion bulb size, which is important because larger onions fetch a higher price. The disease is spread to onions by thrips, and Skeen said many growers in the area started spraying for thrips earlier this season and they sprayed more often. Skeen started spraying 10 days earlier and sprayed every seven to 10 days as opposed to every 14-20 as he has done in past seasons. “I’ve got a good crop coming because I stayed on top of it. I think everybody’s been doing that,” he said.

While onion growers in the Treasure Valley area typically start their thrip spraying programs around Memorial Day, many started in early May this year, said Stuart Reitz, an OSU cropping systems extension agent in Malheur County. While onion growers in this area normally make about six applications for thrips in a season, many have made eight or nine already this year and a few are up to 10, he said. “That helped keep the thrips population down,” Reitz said.

Author: Ellis, S.
Affiliation: Reporter.
Title: Onion virus pressure not as severe as last year.
Source: Capital Press. August 8, 2014.

Do You Want Nematodes with Your Fries?

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Nematode-Damaged Potato

Farmers in Oregon and Washington grow 12 billion pounds of potatoes every year. 90% of this production is for processing into potato chips and fries. 80-90% of the potato acres in Oregon and Washington are fumigated every year to reduce populations of nematodes which are microscopic parasitic worm-like animals that live in the soil and penetrate potatoes underground. Females feed just under the potato skin and deposit 200 to 1000 eggs. Brown spots become evident when the eggs are laid. Growers fumigate the soil to reduce the nematode populations because of the potential for rejection of the potatoes for processing into consumer products.

Columbia root-knot nematode (CRN) infects and develops in potato tubers but does not cause yield loss. Columbia root-knot nematode causes quality defects such as galling on the surface and small brown spots surrounding adult females when peeled. The external and internal defects render tubers unacceptable for fresh market sales and internal defects are unacceptable for processing. For processed potatoes, if between 5% and 15% of the tubers in a field have visual defects the whole-field crop can be substantially devalued or rejected. Based on USDA 2010 yields and prices, the average gross value of potatoes in Idaho was $6,921/ha. The rejection of a potato crop grown on an average 52.6-ha center-pivot-sprinkler-irrigated field represents a loss of $364,000. The potential for dire financial consequences from the presence of CRN in potato tubers is taken very seriously by producers.

Because potential for crop rejection exists with low population levels at planting, fields with any CRN must be treated with a preplant fumigant, nonfumigant nematicides, or both.”

Authors: King, B. A., and J. P. Taberna, Jr.
Affiliation: USDA, Agricultural Research Service, Kimberly, ID
Title: Site-Specific Management of Meloidogyne chitwoodi in Idaho Potatoes Using 1,3-Dichloropropene; Approach, Experiences, and Economics
Source: Journal of Nematology. 2013. 45[3]:202-213.

No Apple Maggots in Northwest Orchards Thanks to Spraying Outside the Orchards

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Apple Maggots

Apple maggot is a native pest of the eastern United States and Canada. In 1979 it was discovered in Oregon and has since moved into California, Washington, and other Western states. Female apple maggot adults deposit eggs singly under the apple skin. Damage is caused when larvae burrow and feed on apple flesh. Browning of the trails occurs as the apple responds to this injury and bacteria associated with maggots cause fruits to rot internally. No Western commercial apples have been infested with maggots thanks to spraying trees outside the orchards to keep them away.

“The first detection of this species [apple maggot] infesting apples in western North America occurred in the United States in Oregon in 1979; flies were caught in neighboring Washington the following year. However, no commercial apples from central Washington, the major apple growing region in the United States, have been found to be infested by R. pomonella, even though adults were first detected within this region in 1995.  

In Washington, an R. pomonella quarantine is established in 22 counties, including two under partial quarantine.

R. pomonella is widespread and abundant in Washington west of the Cascade Mountain range, but is much less abundant in central and eastern Washington except in Spokane County. It occurs in low numbers on the margins of the apple-growing regions in central Washington in native hawthorns and in even lower numbers in unmanaged roadside and backyard apples.

…In the major apple-producing regions of the Pacific Northwest of the United States, control does not occur at the orchard level but rather outside orchards. There is zero tolerance for infested apples. The probability of R. pomonella being moved in apples from Washington to Canada or Mexico is minimized by an extensive annual fly detection and insecticide spray response program conducted by the WSDA and cooperating county pest control boards. …Similar programs exist in Oregon, Idaho, and California.”

Authors: Yee, W. L., et al.
Affiliation: Agricultural Research Service, United States Department of Agriculture
Title: Status of Rhagoletis (Diptera: Tephritidae) Pests in the NAPPO Countries.
Source: J. Econ. Entomol. 2014. 107[1]:11-28.

Eastern Filbert Blight Would Kill All the Western Hazelnut Trees Without Fungicide Sprays

EFB Killing Hazelnut Tree

EFB Killing Hazelnut Tree

Hazelnuts have been commercially produced in Oregon since the early 1900s when they were called “filberts.” In 1981, Oregon “filbert” growers began referring to their crop as “hazelnuts” to be consistent with the rest of the world. Oregon’s hazelnut orchards, concentrated in the Willamette Valley, account for 99% of US production and 5% of world production. Eastern filbert blight is a destructive disease of hazelnut trees that is only present in North America. The disease is known as eastern filbert blight because a shrub harbors the disease in the eastern US. In the 1920s, growers tried to start a hazelnut industry in New York. Filbert blight destroyed the trees. In 1974, the disease was found for the first time in Oregon and has spread throughout the Valley. Without fungicide sprays, the blight would kill the hazelnut trees.

“Eastern filbert blight (EFB) is caused by the fungus Anisogramma anomala…it causes severe perennial cankers, branch die-back, and eventual death of nearly all cultivars of the commercially important European hazelnut, C. avellana. …The pathogen was inadvertently introduced into southwestern Washington in the 1960s and devastated commercial hazelnut orchards because control measures were lacking at the time. It is now widespread across the Willamette Valley of Oregon, where 99% of the U.S. hazelnut crop is produced. Diligent scouting for cankers, extensive pruning, and copious fungicide applications are necessary to continue production in the presence of the fungus.”

Authors: Molnar, T. J., et al.
Affiliation: Department of Plant Biology and Pathology, Rutgers University.
Title: A real-time PCR assay for early detection of eastern filbert blight.
Source: Plant Disease. June 2013. 97[6]:813-818.

Devastating New Potato Disease Has Growers Spraying at First Sign of Vector

Potato psyllids in the Pacific Northwest are spreading a new disease, Zebra chip. Beginning in 2011, psyllid feeding has spread a virus that reduces potato yields and renders tubers unmarketable with bands that darken when fried. Immediate spraying to control the insect vector is required.

“Researchers say populations of potato psyllids – vectors of zebra chip, a crop disease new to the region – are growing dramatically in the Columbia Basin.”

“Despite the increasing psyllid pressure during the past couple of weeks, Phil Hamm, an Oregon State University plant pathologist, believes the disease shouldn’t cause major problems for growers who stick with insecticide programs. … ‘When the region has psyllids, you treat,’ Hamm said.”

Author: John O’Connell
Headline: Psyllid populations growing dramatically
Publication: Capital Press. August 31, 2012.

Want Cranberries from Oregon? Growers Have to Attack Fungal Rots

Cranberries are subject to infections by pathogens that cause rots. These pathogens are controlled with fungicide applications. Under cool, wet spring conditions the disease problem worsens, requiring additional sprays.

“Statewide, the USDA National Agricultural Statistics Service on Aug. 14 projected Oregon’s 2012 cranberry crop at 400,000 barrels, up 11 percent from las year’s 361,000 barrel crop.”

“One drawback for Oregon growers this year has been rising production costs, as growers increased fungicide treatments to avoid losses to disease. Donaldson and Anderson [two Oregon cranberry growers] said they applied between one and two additional fungicide treatments, as a cool, wet spring triggered heavy disease pressure. … ‘For years, I escaped by doing minimal fungicide treatment, but this year we had to attack (the diseases),’ Anderson said.”

Author: Mitch Lies
Headline: Cranberry growers keep an eye on spotty yields.
Publication: Capital Press. Friday, August 24, 2012.

Hazelnuts Free of Filbertworm Damage Require Insecticide Sprays

The cultivated hazelnut was introduced to the west coast of the US during the late 1800s. Oregon’s hazelnut orchards account for 99% of US production and 5% of world production. The filbertworm, which is a native insect generally found on acorns and oaks, is the most severe pest of hazelnuts in Oregon. The females lay eggs on leaves and the new worms penetrate the nut and feed voraciously inside. Consumers prefer hazelnuts free of insect damage – insecticide sprays are necessary.

“In untreated orchards, 20-50% of nuts can become infested with filbertworm larvae. Filbertworm larvae attack hazelnuts in Oregon from June through October, when neonates bore into developing nuts and feed on kernels. … Current filbertworm management relies heavily on synthetic insecticides targeting adults, eggs, and neonate larvae. Growers often apply between one and three sprays per season to keep infestation levels below the economically acceptable threshold of 1%.”

“No effective biological control methods are currently available for this pest.”

Authors: Chambers, U.¹, D.J. Bruck², J. Olsen³ and V.M. Walton¹.
Affiliation: ¹Department of Horticulture, Oregon State University; ²USDA-ARS Horticultural Crops Research Laboratory, Corvallis, OR; ³Yamhill County Extension Service, Oregon State University.
Title: Control of overwintering filbertworm( Lepidoptera: Tortricidae) larvae with Steinernema carpocapsae.
Publication: Journal of Economic Entomology. 2010. 103(2):416-422.

Fungicides Prevent Wheat Losses in the Pacific Northwest – Organic Growers Can Only Pray

Cool, wet weather causes explosions of the stripe rust fungus in wheat fields of the Pacific Northwest. Two articles by Matthew Weaver explain how most growers applied fungicides to prevent yield loss in 2011 while organic growers could only hope that they would not be hit by the disease.

From “Researchers say vigilance against stripe rust a must”:

“Even though there’s more stripe rust in Pacific Northwest wheat fields this year, researchers say the outlook is good -— as long as farmers spray their fields and keep an eye on them.”

“…most growers in Oregon are already on their second application of fungicide and many will make a third application, which is extremely unusual.”

“In most fields, the stripe rust is under control if sprayed. Very few fields haven’t been sprayed, Chen said. Farmers who haven’t should compare the cost of spraying to the potential for yield losses if they don’t, Chen [research plant pathologist with USDA’s ARS] said. ‘It can not only cause a problem in their fields, but also to their neighbors and potentially to the whole region,’ he said, noting rust spores can be carried by the wind.”

From “Rust resistance key to organic wheat survival”:

“Organic wheat growers in the Pacific Northwest are concerned about stripe rust, an epidemic for which they have few treatment options. … Oregon State University wheat breader Mike Flowers said most organic growers were hit by the stripe rust ‘pretty hard’ but losses vary depending on the variety of wheat they grew. … Corvallis, Ore., farmer Clinton Lindsey, farm manager of A2R Farms, said one of his best red wheat fields was ‘completely devastated’ by the rust.”

“There aren’t many options available to organic producers, researchers and farmers say. ‘Pray or not pray,’ said Owen Jorgensen, a Coulee City, Wash., farmer who is on the northern edge of the stripe rust region.” 

Author: Matthew Weaver
Titles:”Researchers say vigilance against stripe rust a must” 27 May, 2011 and “Rust resistance key to organic wheat survival” 8 July, 2011
Publication: Capitol Press