FROM AROUND THE STATE
ISSUE 6 June 5, 2003
Grasshoppers Emerging! There have been numerous reports of grasshoppers hatching in unusually high numbers during the past two weeks. First to third instar grasshoppers can be found in fields with the predominate species being the two_stripped grasshopper. Some hot spots with high numbers are being reported __ northwest of Kramer in Bottineau County (T. Semler) and Mohall to Lansford in Renville County (L. Voigt). Continue to check field for edge activity as they start to move into fields. Economic threshold are 50_75 nymphs (young grasshopper) in edge or 30-45 nymphs in field. In small grains, barley has fewer insecticides registered than wheat. Unfortunately, none of the safer pyrethroids like Warrior or Mustang are legal in barley. Insecticide registered for control of grasshoppers in barley include: dimethoate, ethyl parathion, Furadan, malathion, methyl parathion, and Penncap-M. See the earlier list provided under the entomology heading for other crop options.
Cutworms Active and Threat to Seedling Crops! Cutworms like dingy cutworms are active in agricultural crops, especially sunflowers. The dingy cutworm is an early season cutworm because they overwinter as partially grown larvae. Red*backed cutworm and darksided cutworm are later season cutworms. These cutworms overwinter as eggs and become active later in June. Early instar (young) and later instar (older) larvae of dingy cutworms can both be found in fields, since eggs are laid throughout the fall and larvae will continue to develop until frost. Scout fields by digging around freshly cut plants to find cutworm larvae in soil. Larvae feed at night. Many of our cutworm species are climbing cutworms, which mean they will crawl up and feed on plant leaves. Determine your plant stand and whether you can afford to lose any plants. Economic thresholds for cutworms are: sunflower, canola _ one cutworm larvae per square yard or 25% stand reduction; small grains – 4_5 per square foots; corn – 3_6% of plants are cut; dry bean, soybean – one or more cutworm larvae per 3 feet of row or when 20% of plants are cut; and flax – 10 cutworm larvae per square yard.
Flea Beetles Continue to Damage Canola: Flea beetles continue to be active on canola and mustard. Seed treatments like Helix xtra are providing good protection against flea beetle in later planted canola (planted after the rains). A Crisis Exemption for Mustang Max at 2.24_4.0 fl. oz. per acre was granted for control of flea beetles on mustard until June 13, 2003. Continue to monitor fields until canola/mustard can outgrow the flea beetle damage, usually 4_6 leaf stage. Economic threshold is 25% foliar defoliation.
Diamondback moth on Canola: Diamondback moths are in their second generation flight in ND. Trap catches are been moderate in north central region so far.
Sunflower Beetle Out! Sunflower beetle adults are active and sunflower fields will need to be scouted. Economic threshold is 1-2 adults per sunflower seedling. Most of the pyrethroid insecticides can be tank mixed with herbicide registered in sunflowers. Check label for tank mix compatibility. This is an easy way to control the sunflower beetle problem early.
Painted Lady Butterfly Flying! The spring immigrant, Painted lady butterfly, is here. It does not survive the winters in ND and typically appears at about the time the dandelions bloom in May. Eggs are being laid. These eggs will hatch into the spiny thistle caterpillar, which can be general defoliators of sunflower, soybeans, and other agricultural crops when present in large numbers. Larvae eat Cirsium (thistles) primarily, but also Helianthus (sunflowers) and many other Asteraceae. Look for the silk nest on top of the leaves where it feeds. Use 25% defoliation as a guide for making treatments in sunflowers.
Janet J. Knodel
Area Extension Specialist Crop Protection
North Central Research and Extension Center
During the past week (May 28 to June 3), area rainfall was less than 0.5 inches in the region as recorded at NDAWN (North Dakota Agricultural Weather Network) sites. Topsoil and subsoil moisture continues to be generally adequate. The combination of wet and windy weather has challenged planting, herbicide application in cool-season crops, and haying. Sunshine and warmer weather would be welcome for completing pending field work and established crop development.
Sunflower and bean planting should soon be completed. Alfalfa harvest has begun in areas south of I94.Winter cereals are in the jointing to heading stages. The majority of spring cereals are in the tillering to jointing stages. Yellow small grain continues to be readily found in the region. Wheat and barley are receiving POST nitrogen application to correct N deficiencies or to improve yield potential due to our generally excellent growing conditions for these cool-season crops.
Pest problems include tan spot in wheat and net/spot blotch in barley. Also, leaf rust in wheat was found in Logan County last week. Growers should monitor for grasshoppers, wireworms, and cutworms. Aphids have been found in scattered areas of the state but at very low densities. Weekly results of the NDSU Extension Service IPM crop scouting program can be viewed at
Area Extension Specialist/Cropping Systems
NDSU Carrington Research Extension Center