May 15, 2003

 

NDSU Specialists Points Out Sunflower Threats for 2003

Grasshoppers are the top concern for North Dakota sunflower growers in 2003 followed by the striped flea beetle, red seed weevil, banded sunflower moth and tarnished plant bug, according to Phil Glogoza, North Dakota State University entomologist.

"Grasshoppers are a wide ranging issue," Glogoza says. They not only affect sunflowers but other crops as well. "Grasshoppers are weather dependent and this years conditions are favorable for grasshopper survival," he comments. Grasshopper infestations thrive in years of hot, dry conditions. Rangelands and forage development is poor during these years causing increased migration of grasshoppers to crops including sunflowers.

Glogoza recommends scouting in May and early June to catch infestations early in the season. "It is more economical to catch infestations in the early stages. It requires less insecticide applied to a smaller location," Glogoza says. Growers should be prepared to implement management procedures when young grasshoppers reach threatening levels. One of the first things producers should be aware of is grasshoppers feeding along field margins.

A new concern in 2003 is the striped flea beetle. "This insect is present in North Dakota, however, it has not caused significant damage in past years," says Glogoza. Striped flea beetle infestations have recently been responsible for stand establishment problems in central South Dakota. Striped flea beetle populations were highest in south central counties in North Dakota in 2002. Glogoza cautions producers in this region to be aware of the potential threat.

North Dakota sunflower growers may also face reoccurring seed feeding insect problems including the red seed weevil, banded sunflower moth and tarnished plant bug (Lygus). In 2002, south central counties in North Dakota saw increased red seed weevil infestations. "These counties have high populations of red seed weevil causing us to anticipate potential problems for this year," Glogoza says. Other regions across North Dakota are also susceptible, however they are at lower risk.

The banded sunflower moth has a widespread presence across North Dakota. It invades during the early reproductive stages of the sunflower. This makes early detection very important for producers. Finding the banded moths in grassy field margins is often the first indication that the insect is active in the area.

The tarnished plant bug (Lygus) damages confection sunflowers used for consumption and hulling. The insects feeding causes a symptom referred to as kernel brown spot, which reduces seed quality. In 2002, tarnished plant bug infestations were most severe in northern and eastern parts of the state. "Areas of greater crop diversity are where the Lygus problems occur, particularly in areas with broadleaf row crops and alfalfa," Glogoza says.

Glogoza recommends a treatment plan for managing red seed weevil, banded sunflower moth and tarnished plant bug in confection sunflowers and those sold for hulling. This program incorporates two sprayings, one during early flowering and again seven to ten days later. Since all three insects invade during the same time frame, this program protects against feeding damage from all three.

"In sunflowers grown for oil seeds, producers need to scout early in the season to determine if infestations of seed weevil and banded moth are present. They then need to respond according to thresholds. "Early detection is key to controlling infestations," Glogoza says.

For more information on sunflower pests contact Phil Glogoza at p.glogoza@ndsuext.nodak.edu  or (701) 231-7581 or your county extension agent. Maps outlining pest infestations in 2002 can be accessed through the following website: http://134.129.78.3/sunflower. Other information can be located on the National Sunflower Association website at www.sunflowernsa.com .

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Source: Phil Glogoza, (701) 231-7581, p.glogoza@ndsuext.nodak.edu
Writer: Deana Oe, (701) 231-8371, deana.oe@ndsu.nodak.edu
Editor: Tom Jirik, (701) 231-9629, tjirik@ndsuext.nodak.edu