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ISSUE 5  May 31, 2001


SCOUT CANOLA FIELDS
FOR FLEA BEETLE INJURY

Recent rains this past week appears to have stimulated flea beetle emergence. In my research plots at the NCREC in Minot, flea beetle numbers and injury were very low prior to the rains. Since the rains, injury has increased significantly in the plots. However, sticky cards still indicate that flea beetle population levels are considerably low. It appears that the beetles move over the ground during periods of cool temps, that we had this past week, and that sticky traps may not be a good indicator of flea beetle populations and potential injury during cool periods. In addition to the sticky cards, fields need to be monitored for flea beetle injury during these cool periods.

Denise Olson
Assistant Professor Entomology

 

HIGH RISK PLANTING DATES FOR WHEAT AND WHEAT MIDGE, 2001

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We have reached the point where 600 degree days (40 F) have been accumulated around the state. The first date corresponds with the accumulation of 200 DD; the second is when 600 DD were reached. Now is a good time to review planting dates for individual fields, and begin to prioritize scouting efforts for adult midge based on those planting dates and expected head emergence.

For more information on wheat midge, visit the midge web site for updates and degree day information to watch when midge emergence begins in your area.

http://www.ag.ndsu.nodak.edu/aginfo/entomology/entupdates/Wheat_Midge/owbm.htm

 

CEREAL LEAF BEETLE -FURADAN 4F LABELED FOR SMALL GRAINS

A state 2(ee) label has been issued for the use of Furadan 4F to control cereal leaf beetle in small grains. The label applies to wheat, barley, and oats. The label has been issued for the states of North Dakota, Montana, South Dakota, Wyoming, and Idaho.

Furadan is labeled at 1/2 pint per acre. Treatment must be made prior to heads emerging from the boot. Do not make more than two applications per season. See the label for additional restrictions and recommendations.

In the event that any of our small grain growers in northwest ND or neighboring states would need to use this product, they must have in their possession a copy of the label. It may be found at the NDSU Pesticide Training and Certification web page. Follow the link to "Pesticide Label Search". From there, you can access this and other special pesticide labels issued for North Dakota

http://www.ag.ndsu.nodak.edu/aginfo/pesticid/pesticid.htm

 

CUTWORMS . . . TIME TO WATCH FOR INCREASING ACTIVITY

Reports of cutworm activity continue to be few and far between. However, we have reached the time of the season when second wave of cutworm activity gets underway. The cutworms that will make their presence known in the next ten days are the species that overwinter as eggs and are now hatching. The most familiar cutworm will be the Redbacked cutworm. They pose the greatest risk to our row crops that are just emerging or now being planted.

 

ARMYWORMS IN OUR FUTURE ?

Remember the major infestation of armyworms that hit northwest MN small grains in early July ? Donít panic, there are no reports of armyworm in the region. However, armyworms in large numbers are being reported in pasture and small grains in the states of Oklahoma, Missouri, and Arkansas. Though these reports do not mean impending disaster, it is worth noting for future reference. The armyworms in those areas become moths that can migrate into the region. The weather patterns must assist their migration. Still lots of "what ifís", but one we are watching.

 

MONITOR ALFALFA FOR LEAFHOPPERS, WEEVILS AND LEAFMINERS

No reports of problems in alfalfa. As we approach the first cutting, there are some scouting activities that should be scheduled.

Alfalfa weevil should be feeding at this time. Monitor tip injury to assess pre-harvest damage. This method is relatively simple and provides adequate estimates for the pre-harvest damage potential from alfalfa weevil when planning management decisions.

Select 50-100 alfalfa stems, (10 to 20 randomly selected stems from each of 5 locations) and examine for signs of feeding damage in the leafbuds and growing tip leaves. Divide the number of stems with recent tip injury by the total stems collected, convert to a percent, and compare with the threshold.

For post-harvest weevil management, monitor regrowth for potential stubble infestations, particularly beneath windrows. After the hay has been picked up, sample the stubble and early regrowth in 20 one square foot samples, 4 chosen randomly from 5 locations. When regrowth after harvest is sufficiently tall, go back to monitoring tip injury.

Insecticides labeled for alfalfa weevil include Baythroid, carbaryl (Sevin), Furadan, Imidan, Lorsban, malathion, methyl parathion (including Penncap M), permethrin (Ambush and Pounce), and Warrior.

Alfalfa Weevil thresholds

Before 1st Cutting

35% (weak stand) plants with feeding damage

40% (vigorous stand) plants with feeding damage and/or 2 live larvae/stem

After 1st Cutting in stubble

8 or more larvae/ft2, (6/ft2 on sandy soil); or larvae are suppressing regrowth

Finally, watch for the Alfalfa blotch leafminer in the eastern half of ND. Very little activity by the leafminer has been observed since problems in 1999. Infested fields take on a whitish cast due to extensive infestations of this fly pest. The same field appearance can be confused with alfalfa weevil feeding, however, leafminer damaged leaves are not ragged or skeletonized.

The first signs of an infestation are "pinholes" in the leaves, caused by the adult fly, and a comma shaped mine formed by the larva tunneling through the leaf. The pinholes are easily visible if you hold the leaf up against the sunlight.

Insecticides have not provided consistent or significant control. The best recommendation would be to cut a little early to avoid leaf loss from rapid drying due to the larval mines. Early harvest in either the first or second cut should reduce the future generations in the season.

FORAGE CROP INSECTS

Insecticide

Alfalfa Weevil

Alfalfa Blotch Leafminer

Pea Aphid

Leafhopper

Cutworm

Grasshopper Forage

Grasshopper Pasture

Lygus or Plant Bugs

Baythroid

M

M

M

M

       

Capture 2EC

 

 

 

 

     

M

carbaryl (Sevin)

M

 

M

M

M

M

M

 

dimethoate (Digon 400, Dimethoate 400)

 

 

M

M

 

M

 

M

Furadan 4F (alfalfa only)

M

M

M

M

 

M

 

M

Imidan 50 WP

M

 

M

 

 

 

 

 

Lannate LV

 

M

M

M

M

 

 

M

Lannate

M

 

 

 

 

 

 

 

Lorsban 4E (alfalfa only)

M

M

M

M

M

M

 

M

Malathion ULV

 

 

 

 

 

M

 

 

Malathion 57EC

M

 

M

M

 

M

M

M

Malathion ULV 95% Tech.

 

 

 

 

 

 

M

 

Methoxychlor 2EC

M

 

 

 

 

 

 

 

Methyl parathion 8EC

 

 

 

 

 

M

 

 

Methyl parathion 7.5EC

M

 

 

 

 

 

 

 

Parathion 8EC

 

 

M

M

 

 

 

 

Penncap-M

M

M

M

M

 

M

M

 

permethrin (Ambush 2E, Pounce 3.2EC)

M

 

M

M

M

 

 

M

Warrior

M

M

M

M

M

M

 

M

Phillip Glogoza
Extension Entomologist
pglogoza@ndsuext.nodak.edu


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