New Fungicides Improve Management of Vomitoxin

Fusarium Head Blight

Fusarium Head Blight

Fusarium Head Blight (FHB), also known as scab, is a destructive disease of wheat and other small grains. In the spring, ascospores and/or conidia are released from crop residues and are spread by wind or splashing water. They land on wheat heads and during wet, warm weather they germinate and infect glumes, flower parts, or other parts of the head.

In addition to lowering grain yield and quality, F. graminearum produces mycotoxins, primarily the trichothecenes deoxynivalenol (DON), nivalenol (NIV) and T-2 toxin. …These mycotoxins are harmful to humans and livestock. In North America, DON, also known as vomitoxin, is the most common and economically important mycotoxin found In Fusarium-infected wheat. …Grain with high concentrations of DON often is discounted or rejected at the elevator, which exacerbates the losses incurred by the farmer.

“In the U.S., a less than desirable number of current commercial wheat cultivars have moderate resistance to FHB and this resistance can be overwhelmed in years with high disease intensity. Fungicides are often applied to control FHB when favorable conditions for disease development are forecast.

Over the last two decades, there has been considerable improvement in the effectiveness of fungicides in controlling FHB and DON. This improvement is attributable in part to improved fungicide chemistries and greater knowledge gained through research on fungicide application rates, timing, and technology.

The best approach to managing FHB is to integrate available management strategies. Research has shown that integrating cultivar resistance with fungicide application can be effective management strategy for FHB.

Availability of moderately resistant cultivars and new fungicide chemistries coupled with improved fungicide application technology has led to greater farmer adoption of an integrated strategy in the management of FHB and DON.”

Authors: Wegulo, S. N., et al.
Affiliation: Department of Plant Pathology, University of Nebraska-Lincoln.
Title: Integration of fungicide application and cultivar resistance to manage fusarium head blight in wheat.
Source: InTech. Fungicides – Showcases of Integrated Plant Disease Management from Around the World. Available at: http://www.intechopen.com/books/fungicides-showcases-of-integrated-plant-disease-management-from-around-the-world

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Consumers Want Perfect Sunflower Seeds as Snack Foods: Insecticides Make It Happen

Seed Weevil

Seed Weevil

The sunflower is the only row crop in North America that coexists with its native ancestors. When extensive commercial planting of sunflower began in the 1970s, many of the insects which evolved in native perennial sunflower seed species transferred to the cultivated crop. Red sunflower seed weevils deposit eggs in sunflower seeds and larvae feed on the developing sunflower kernels destroying a portion of the kernel. The larvae make an exit hole and exit the seeds in late summer. Research indicates that most seeds are only partially fed upon.

“Several years ago, a set of trade standards were developed for nonoil sunflower kernels. These standards stipulate there should be no more than 10 percent broken kernels; not more than 0.5 percent heat damage; and not more than two percent insect damage.

Economic populations of seed feeders such as the red and gray seed weevils, head moth and banded sunflower moth can inflict very serious damage if not controlled. But they commonly consume just a portion of the kernel, so those seeds often are not separated from other seeds during combining. “It’s very difficult to remove all insect damage from in-shell sunflower,” affirms Jim Krogh, president of Agway, Inc., of Grandin, N.D. “Yet it’s also difficult to explain to today’s consumer why there’s a hole in the seed they bought. The hole is unsightly; the kernel tastes bad. It’s a bad deal all around.”

Since it is an edible product, economic thresholds for confection flowers are much lower than for oil-types. One to two weevils per plant should trigger prompt insecticide treatment, based on current recommendations.”

Author: Lilleboe, D.
Affiliation: Writer
Title: Optimizing the quality of your confection crop
Source: The Sunflower. April/May 1998. Available online at: https://www.sunflowernsa.com/magazine/details.asp?ID=77&Cat=10

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.

Cancellation of Effective Insecticides Puts Carrots at Risk of Rejection by Food Companies

The carrot weevil is native to northeastern North America. Each female can lay 300 eggs. After hatching and entering the carrot, the larvae tunnel through the carrot, filling the tunnels with excreta. The epidermal cells around the tunnels die and become dark brown. The presence of larvae, excreta and feeding damage are of major concern to carrot processors because of strict FDA quality control in processed foods. Processors are unwilling to accept carrots if they find one live larva in a sample or if the carrots have more than 1% damage. Since the 1940s, effective broad spectrum insecticides kept carrot weevil damage to a minimum; however, the most effective insecticides have been cancelled for use in the US.

“Adults [carrot weevils] overwinter in and near carrot fields where carrots were grown the previous year, emerging in late April to early May in New Jersey. The adults feed directly on the leaves and crowns of carrots, and females oviposit from the beginning of May until late June in carrot roots. Larvae tunnel extensively throughout the upper third of the roots, damaging 80% or more of the carrots in untreated processing carrot fields.”

“Consequently, pesticide applications are directed at adult weevils to prevent or reduce oviposition. … However, during the past several years, carrot weevil damage has been increasing in New Jersey carrot farms, and the damage has been as high as 90% loss on farms in Salem County. These losses are partly due to the cancellation of broad-spectrum insecticides, such as parathion, azinphos-methyl, and phosmet during the early 1990s.”

Authors: G.M. Ghidiu¹, E. Hitchner², M. Zimmerman¹ and E. Rossell¹
Affiliations: ¹Rutgers University; ²Virginia Tech
Title: Effect of two different nozzle arrangements on control of carrot weevil, Listronotus oregonensis (LeConte), in processing carrots.
Publication: Plant Health Progress. April 3, 2006.

North American Ginseng Production Depends on Fumigation

Roots of American ginseng are common ingredients in herbal medicines. However, being a root crop subjects ginseng to attacks by soil-dwelling organisms, which cause root rot of ginseng seedlings. In order to prevent damage to the roots, growers typically fumigate fields before the ginseng crop is planted.

“An important component of many traditional Asian herbal medicines is dried root of American ginseng (Panax quinquefolius L.). … Although indigenous to the forests of eastern North America, most of the world supply of dried root is now provided by crops grown in cultivated fields under artificial shade structures. Over two-thirds of Canada’s ginseng crop is grown in the sandy soils of southwestern Ontario.”

“Current production methods provide environments favourable to disease development, and crop loss due to disease is significant. Although ginseng germplasm is diverse, disease-resistant cultivars are not available. … To reduce risk of damage from soilborne species of Pythium and nematodes, ginseng growers normally fumigate fields prior to seeding.” 

Authors: R.D. Reeleder¹, J. Miller¹, B. Capell¹ and J. Schooley²
Affiliation: ¹Agriculture and Agri-Food Canada, Ontario, Canada; ²Ontario Ministry of Agriculture, Ontario, Canada.
Title: Mefenoxan sensitivity and the impact of fumigation on Pythium species and Phytophthora cactorum in ginseng soils.
Publication: Canadian Journal of Plant Pathology. (2007) 29:427-436.