North Dakota State University Extension Service - Burke County |
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Burke County AgAlert |
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July 8, 2004 GRASSHOPPERS The warmer weather has brought increased grasshopper hatching and activity. At the present time, I expect little damage to be occurring in crops except possibly sunflowers. As more of the PP acres are sprayed or worked you should be watching your field borders for potential migration into acres of green plants. There are a wide variety of insecticides available like Sevin, Asana, Warrior, Mustang and other which are broad spectrum. There is also a newly released product called Dimilin which prevents grasshoppers from molting. Because of the way it works it does not kill beneficial insects. The following information about Dimilin is provided by Phil Glogoza, NDSU Extension Entomologist: Dimilin (diflubenzuron): Crompton Uniroyal Chemical Grasshopper susceptible stage: Best results will occur when grasshoppers are in the 2nd to 4th instar stages. The growth stage between each molt is called an "instar." On average, grasshoppers will molt every six to nine days. Mode of Action: Dimilin disrupts the formation and deposition of chitin in the grasshopper's exoskeleton, interrupts the grasshopper nymph's ability to molt, and affects its coordination and feeding habits. How long before seeing control effects? Grasshoppers must feed on dimilin and then molt before populations are reduced. Effects of treatment typically being to appear within five to seven days after treatment, as the grasshopper nymphs fail to molt and die. In addition, dimilin causes grasshoppers to become malformed, and to exhibit impaired coordination and feeding habits. This makes them easy prey for natural predators like ground beetles. Any control with adults? Dimilin does NOT control the adults. However, the consumption of dimilin by adults reduces their feeding rates, escape behavior as well as mating and egg production. How long is the residual? Dimilin remains active on the plant tissue for at least one full month. That means it's still present to control delayed hatching nymphs, later hatching grasshopper species, and secondary infestations that may occur during this 30 day period. Rainfast? Dimilin is rainfast and it will continue to control grasshoppers well after rains have occurred. Safety? Dimilin is safe to livestock, birds, fish, honey bees, and beneficial insects. It also had low mammalian toxicity and is low risk for the pesticide applicator. Dimilin can be applied while bees are actively foraging. Dimilin is toxic to aquatic invertebrate animals. It should NOT be applied by ground within 25 feet, or by air within 150 feet of bodies of water including lakes, reservoirs, natural ponds, marshes, rivers, or streams. Preharvest interval? NO haying or grazing restriction except on alfalfa forage. Observe a one-day preharvest interval when cutting alfalfa forage. There is no need to relocate cattle or other livestock when dimilin is applied. What is the cost? Earlier estimates of Dimilin 2L costs were about $221
per gallon. So, a 1 fl oz per acre rate would cost about $1.72 and 2 fl oz
per acre about $3.45 per acre. Current leaf and head disease prediction information is available at www.ag.ndsu.nodak.edu/cropdisease/cropdisease.htm or you can get recorded information via telephone at 1-888-248-7382. The following information about the disease forecasting system is from Dr Shaukat Ali: Automated computer models for Fusarium head blight (scab) and leaf
diseases are now activated. Attention: This year an improved computer model
for Fusarium head blight forecasts will be used. This model has about 80%
accuracy to predict epidemics and non-epidemics. Fusarium spore counts will
not be used as a component of the system in 2004. A 1-800 telephone service
has also been activated for the current forecasts information. If you have
any questions about the system, contact the Department of Plant Pathology,
NDSU, Fargo, ND 58105 (701-231-6467).IPM scouts surveyed 130 wheat fields
for various diseases during the first week of July. Tan spot was still the
most common disease observed in majority of the fields surveyed. An
increasing trend in leaf rust incidence was also observed in the surveyed
area. Dr. McMullen and some crop consultants observed stripe rust in some
fields in the SE area. Read this week's pest report for more information on
barley and wheat diseases. FOXTAIL MILLETS FOR HAY (Dr. Duane R. Berglund NDSU Ext Agronomist) Foxtail millets are grown primarily for short season emergency hay crops. Several landraces have been developed over time and are grown in North Dakota. Planting of foxtail millets can be delayed until mid-June into early July. When used for emergency hay production, late planting is usually encountered. Plant into moist soil about 1 inch deep. Shallower seeding may be
desirable on heavy textured soils with good moisture. Germination is fairly
rapid but early seedling vigor is lacking. Foxtail millets have low seedling
vigor and in general are poor competitors with weeds. A seeding rate of 15
to 30 pounds per acre is recommended. The higher rates are recommended in
eastern North Dakota with the higher rainfall potential. In western North
Dakota, 15 pounds is adequate on weed free fields. Common Foxtail millet is fine-stemmed and leafy. Seed head is cylindrical and compact and tapers toward the tip. The lower portion is less compact than the mid-and tip portions. Seed head varies from 5/8 to 3/4 inch in diameter and 4 to 6 inches in length with pale yellow bristles. It is one of the earliest foxtail millets, maturing in about 70 days and producing a hay crop in about 50 days. Siberian millet has medium-sized stems and possesses some drought tolerance. The seed head is cylindrical, 5/8 to 3/4 inch in diameter, 4 to 6 inches long, and has purple bristles. It matures in about 75 to 80 days and produces a hay crop in 55 to 60 days. Manta, a South Dakota release, is an early Siberian millet. Hungarian millet is characterized by a small, compact, slightly lobed seed head which is 1/2 to 5/8 inch in diameter and 4 to 6 inches long. Bristles vary in color from clear to pale yellow through purple and black. Stems are medium in size. It is reported to do better under more favorable moisture conditions. Maturity is about 70 days and a hay crop can be ready in about 55 days. German millet has thicker stems and broader leaves. The seed head is distinctly lobed, measuring 1 to 1 ½ inches in diameter and 6 to 9 inches long. Bristles are greenish to purple. It is a longer season foxtail, which takes about 90 or more days to mature and 65 to 70 days to produce a hay crop. Because of its increased stem size, it takes better management than the other foxtail millets to produce good quality hay. Harvest hay millets in the late boot to early bloom growth stage. Any
delay after full head emergence will reduce quality. Bristles become hard as
maturity approaches and may cause sore mouth, lump jaw and eye infections
when fed to livestock. Hay protein content is highest when the ratio of
leaves to stems is high. Curing foxtail millet requires attention as light
stands tend to sun dry rapidly after cutting, while heavy stands, especially
of the German type, cure at a slower rate. If expected yield levels are
greater than 1 ½ tons per acre, crimping will help the curing process.
Potential yield of foxtail millet hay is influenced by moisture
relationships. Research trial yields from NDSU Research/Extension Centers
have ranged from 1.5 to 3.4 tons/acre. I’ve seen several spruce trees infested with these small green worms
feeding on the young needles. If you haven’t yet sprayed your trees, I
suggest you do it soon. Not much damage has occurred yet but if you wait
until the worms are big enough to easily see, they can do a great deal of
damage. Many spruce trees in the area suffered a lot of sun scald or winter
burn this past winter and the additional stress of defoliation by spruce
sawfly could be enough to kill many of them. Dan Folske |
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