Increasing population densities of grasshoppers in pasture and field crops, including alfalfa, have been observed. At this time of year, development is mostly in the first to third instar making now a good time to evaluate control options.

Producers should not wait until grasshoppers have reached the winged adult stage in early to mid-July, when control is more difficult. As winged adults, grasshoppers are more mobile and able to fly long distances searching for food. Grasshoppers normally build along field edges, and that is the best place to scout and treat when high numbers begin developing.

Treating border areas is much cheaper than treating whole fields.

Life Cycle and Damage. Grasshopper species that damage field crops such as alfalfa typically complete one generation per year.

In Oklahoma, three of the most common species are the differential, twostriped, and red-legged grasshoppers. These grasshoppers overwinter as eggs laid in soil, usually along fences, roadsides, and in pastures rather than in field crops. Nymphs hatch from these eggs in late spring (May and June) and feed on grass and broadleaf weeds outside of fields until mid-summer when they become large nymphs or adults.

As plants in non-cropland areas typically mature and become less palatable, grasshoppers then begin migration into adjacent fields and, depending upon population densities, may feed extensively on alfalfa or other available crops. While potential defoliation of alfalfa is a concern, they also pose a serious problem in seed production because they often feed primarily on fruiting structures once alfalfa is in bloom and can cause 100% loss of the seed crop, especially near field edges.

Sampling and Control. Grasshopper population densities are typically estimated while walking in areas near field margins. As grasshoppers fly out of foliage, numbers per square yard are estimated.

The listed economic threshold for spraying to control grasshoppers in alfalfa forage production is 15-20 hoppers/sq. yd. However, this does not apply to seed production. After alfalfa begins flowering, the aforementioned levels may result in seed losses greatly exceeding the cost of control.

It is critical that grasshoppers be controlled in adjacent fence-rows, pastures, and other surrounding areas before migration into alfalfa begins.

Controlling grasshoppers in areas adjacent to fields in June is effective since hoppers are sprayed while they are still small nymphs. Applications made at this time may prevent serious losses in seed production later and preserve pollinators. Additional information on control of grasshoppers can be found in OSU Extension Factsheet No. 7150.

Nitrate Management Scenarios for Livestock

The objective of this section is to present four scenarios selected to illustrate the major concerns relative to a specific situation and the types of management that could be applied to minimize the effects of nitrate consumption.

Scenario 1: High nitrate hay as an emergency feed for beef cows.

Concerns:

What is the stage of production (month relative to calving date)?

What is the nitrate content of the hay?

How much hay will the cows eat?

Management:

Determine susceptibility of cows based on stage or production. Calculate potential nitrate from hay nitrate analysis and projected hay intake.

Sort bales by nitrate content:

• Feed low to moderate nitrate bales (<10,000 ppm) as emergency feeds. Feed higher bales (>10,000 ppm) as a supplemental feed (4-8 lb/cow/day).

• Consider discarding extremely high nitrate bales (25,000 ppm).

Consider some combination of the following:

Watch weather and start feeding low to moderate nitrate hay prior to inclement weather to adapt ruminal microorganisms to nitrate. Slowly increase feeding level so that cows are adapted by the time the storm arrives. During snow or ice cover, cows can consume an extremely large quantity of hay (25-35 lb/cow). If hay is fed during cold, open weather, intake will likely be less (8-15 lb/cow) and dependent on feeding rate.

Feed high energy grain cubes to dilute nitrate intake and provide energy to stimulate microbial detoxification of nitrate.

Establish propionibacteria (feed for 8 days or give gel paste) prior to nitrate exposure to minimize the effects of nitrate intake.

Scenario 2: High nitrate hay as a supplemental feed for wintering beef cows

Concerns:

What is the nitrate content of hay?

How much hay do the cows need to eat?

Management:

Determine the potential nitrate exposure based on hay intake and forage nitrate concentrations.

Sort bales by nitrate content:

• Feed low to moderate nitrate bales (<10,000 ppm) as emergency feeds.

• Feed high nitrate bales (>10,000 ppm) as a supplemental feed (4-8 lb/cow/day).

• Discard extremely high nitrate (25,000 ppm) hay.

Consider some combination of the following:

Adapt cattle with low to moderate nitrate hay by slowly increasing the feeding level.

Feed high energy grain cubes to dilute nitrate intake and provide energy to stimulate microbial detoxification of nitrate.

Establish propionibacteria (feed for 8 days or give gel paste) to minimize the effects of nitrate intake.

Scenario 3: Summer grazing of sorghum/sudan by beef stockers

Concerns:

What is the nitrate potential?

Have cattle recovered from shipping stress?

Management:

Evaluate the potential nitrate exposure based on environmental conditions and previous management decisions. Stressed, hungry cattle should not be released directly on to potentially toxic forage. If necessary, delay release. Use the opportunity to put the cattle through a recovery program so that ruminal function and health status are normal. Consider some combination of the following:

Adapt cattle to nitrate by increasing levels of high nitrate feeds harvested in previous years.

Adapt cattle to sorghum/sudan forage by progressive limit grazing for 5 to 7 days.

Feed a high energy receiving ration to stimulate ruminal recovery and increase ruminal energy prior to release.

Feed frequently to disrupt grazing patterns and provide a fill.

Establish propionibacteria (feed for 8 days or give gel paste) to minimize the effects of nitrate intake.

Consider releasing in the afternoon when cattle are full and appetite is low.

Scenario 4: Dairy cows are fed a diet that contains 50% corn silage (DM basis) harvested during a dry summer and consume water that is known to be high in nitrate.

Concerns:

What is the nitrate content of the corn silage?

What is the nitrate content of the water?

Management:

Calculate total nitrate intake to evaluate risk.

Silage nitrate concentration: 10,000 ppm

Water nitrate concentration: 200 ppm

A 1,500 lb. holstein producing 100 lbs. milk/day will consume about 58 lbs. dry feed and 40 gallons of water.

58 lbs. Dm x 50% silage = 29 lbs. DM from silage

29 lbs. Dm x 10,000 ppm or 1.0% (.01) nitrate= .29 lbs. nitrate

.29 lb. nitrate x 454 grams per lb. = 131.66 grams nitrate

Total nitrate from silage = 131.66 grams per day

40 gallons of water x 8 lbs. per gallon = 320 lbs. of water

320 lbs. water x 200 ppm or .02% (.0002) nitrate = .064 lb. nitrate

.064 lb. nitrate x 454 grams per lb = 29.06 grams nitrate

Total nitrate from water = 29.06 grams nitrate per day

Total nitrate intake per day (silage + water) = 160.66 grams

58 lbs. DM feed x 454 grams/lb. = 26332 grams of feed per day

160.66 grams nitrate/26332 grams feed per day = 6101 ppm nitrate in total diet 

This quantity of nitrate is within the range where milk production may be reduced and although unlikely, mid-to-late term abortions may occur. Acute toxicity, however, is even less likely to occur.

Evaluate alternative roughage sources. To completely compensate for water nitrate, silage intake must be reduced by 75 percent and replaced by another high quality forage.

This level of corn silage may not be worth the trouble. Perhaps other, low nitrate forages should be purchased for use with the high producing cows. The higher nitrate corn silage could be mixed with other low nitrate forage for dry cows or other less productive animals.

Evaluate alternative water sources. If wells are the water source, consider drilling a deeper well to potentially draw lower nitrate water. Also, evaluate other water sources such as rural or city water. If surface water is used, determine the source of the nitrates (manure runoff, excess fertilizer, etc) and attempt to control the nitrate source.

Establish propionibacteria (feed for 8 days or give gel paste) to reduce nitrate effects in the rumen. Caution: Propionibacteria do not have a demonstrated effect on subacute nitrate toxicity. Observe milk production closely when starting to feed high nitrate forages to lactating dairy cows. If a dramatic drop in milk production is noted, consider purchasing alternative forages immediately.

4-H

Payne County 4-H needs your help! Tassi Jo, a Payne County 4-H member, is conducting a county wide community service project! Payne County 4-H is collecting items for the Stillwater Humane Society. Items such as dog food (adult and puppy), cat food (adult and kitten), cat and dog toys, cleaning supplies, leashes, etc. are needed.

Items can be dropped off at the Payne County Extension office before June 30th at noon. If you would like to donate and have more questions, please contact the Payne County Extension office at 405-747-832.

Ag Corner is provided by Payne County Extension Educators: Nathan Anderson, Agriculture; Dea Rash, FCS; Keith Reed, Horticulture  and Summer Leister, 4-H.

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