Callaway County

When forages, especially grasses, are stressed by drought, they can accumulate nitrates. Excess nitrates can poison livestock. It is not the nitrate that is actually toxic but nitrites. Nitrates (NO3) are converted to nitrites (NO2) by bacteria in the rumen (stomach). The nitrites are then changed to ammonia (NH3), which are used to make proteins. Excess nitrites are taken up by hemoglobin in the blood and methemoglobin is formed. Methemoglobin does not allow the blood to take up oxygen and does not easily convert back to hemoglobin. Nitrate poisoned animals suffocate.

Corn often has high nitrates when salvaged for forage use during a drought. When moisture stress and high temperatures have limited kernel set on ears, the nitrates are not allowed to convert into proteins and accumulate in the stem. Typically, corn grown for grain has high amounts of nitrogen fertilizer applied to produce maximum yields. A high level of nitrogen fertilization also is a factor in many cases of nitrate poisoning.

Farmers can tell if forages are safe or need further testing by taking samples of forages to their local Extension Center for a diphenylamine nitrate test. Forage samples should be taken from several places in a field especially if some plants are more stressed than others. Forage plants should be cut off at ground level. The diphenylamine solution quickly turns dark blue in the presence of high nitrates in the forage plant’s tissue. The height off the ground nitrates indications are found suggests the increased poisonings danger. Forages considered to have high nitrates should be tested at a laboratory to evaluate the level of danger. Very high levels mean those forages should not be used to feed livestock.

Forages with high nitrate levels may be acceptable for silage. During the ensiling process, about half nitrates are convert a gasses, nitrogen dioxide (NO₂) and nitrogen tetroxide (N₂O₄). These gasses are toxic and can accumulate upright silos or in low areas of pit silos. Still, this may be a way to further salvage drought damaged corn or forages. A feed laboratory must test silage from high nitrate forages to evaluate feeding safety. My news article from a year ago, August 7^th, cover-making silage from drought stressed corn. It is available from the Callaway County Extension Web Page at: http://extension.missouri.edu/callaway/agriculture.shtml.

The source of information for this article is Jim Jarman, Agronomy Specialists (573) 642-0755 and Rob Kallenbach, Assistant Professor of Agronomy 573-882-2801.

Blister beetles are out and about. They are also known as the "old fashion potato bug (beetle)". As their name implies, blister beetles can cause our skin to blister or raise a red irritated spot. When disturbed, blister beetles bleed at their joints. The blood contains a strong toxin called cantharidin. Try to keep a safe distance away from blister beetles. If you are not sure what they look like, contact the Callaway County Extension Center for a description or come by to look at a photograph.

A serious problem caused by blister beetles is when they are bailed in alfalfa hay eaten by horses. Eating blister beetles will kill or make horses seriously sick. Most other livestock are not as sensitive to blister beetle poisoning. Although, Recent deaths in pastured poultry has been attributed to blister beetles. Pastured poultry is becoming more popular especially on small farms. One of the attractions of growing chickens and other fowl on pasture is they being raised more like in the "good ole days". Small farms with pastured poultry need to be aware of this potential threat. More information on this subject is available from the Extension Center. Contact Jim Jarman, Agronomy Specialist (573) 642-0755.

Cole and Boone Counties will be hosting beginning Master Gardener Classes starting in late August and early September. Contact those offices or the Callaway County Extension Center for more information.

University of Missouri Extension programs are open to all.

More Drought Related Issues   August 13, 2003

If you don’t like the weather in Missouri, all you have to do wait and it will change unless there’s a drought. I have gone over some drought related information to cover the high points. If anyone needs more information, don’t hesitate to call or drop by.

Since last week, I have heard of farmers farther north and west using nitrate laced crops for forage because they have run out of pasture and hay. This is a poor excuse for feeding poison to livestock. Buy hay for now and make silage for later is much better management.

Most herbicides are broken down by living soil microorganisms. Much like plants, microorganisms require favorable temperature and moisture to function. Conditions that inhibit these activities also reduce the organisms' ability to decompose organic matter and herbicides. Begin thinking about a dry and cool winter. Herbicide carryover can result and injure the following year's crop. Check labels for warning statements on carryover, long replanting precautions and suggested crop rotations. An easy way to check for carryover is to bring a soil sample inside during the winter and plant some crop seeds. If they die or do poorly, some thought should be given to carryover problems.

Drought conditions may make toxic plants attractive enough to poison livestock. Try to avoid turning livestock into pastures where poisonous plants occur. Also, making hay, cutting green chop or silage containing poisonous plants is especially risky. Attractive forage may mask the poisonous plants encouraging livestock to consume toxic levels.

Several species of poisonous plants are distributed throughout Missouri and many of them are commonly found in native and improved pastures.

Poisonous plants commonly have a disagreeable taste that usually keeps livestock from grazing them. Drought stressed forage and overgrazing may force livestock to try plants they usually avoid. Some species are poisonous only during certain stages of growth like the common cocklebur. It is most poisonous shortly before reaching the two-leaf stage. At this growth stage, cocklebur is exceedingly toxic to pigs but can also harm cattle and sheep. Young, second growth or drought stressed sorghum is another example of toxicity during specific growth periods.

It may be easier to find toxic weeds by looking where they are most likely to grow. Jimsonweed, snow-on-the-mountain, croton and wild indigo are commonly found in open areas of the pasture. Shade-loving weeds include white snakeroot, bracken fern, pokeweed and buckeye. Black nightshade, water and poison hemlock, and horsetail grow in moist areas and along creeks or ditches. Poisonous plants found in cultivated fields include cocklebur, jimsonweed, milkweed, pigweed and Johnson grass. Wild cherry poison ivy, milkweed, and pokeweed are found along fences and hedgerows.

A continued drought means some thought may be needed on nutrient management. Crops not using nutrients to make grain will leave more soil fertility than in more normal growing seasons. There are charts to estimate the amount of fertility removed by crops by yield. Different methods of handling damaged crops are bailing or grazing corn stubble, bailing soybean stubble or whole soybeans and taking silage. An estimate of nutrient removal is available for all these methods. Soil and tissue tests are another method that may give better estimates.

Aflatoxin in corn is produced by a fungus stimulated by hot, dry conditions and the damage caused by drought. Insect, bird, and mechanical grain damage helps this fungus to grow. Dry corn quickly since the mold grows best when 18% moisture corn is stored at 86 F. Store drought damaged grain separately from healthy grain. Adjust combines to minimize damaged and separate out damaged kernels. Manage grain to keep grain at proper moisture, minimize insects and moisture migration. It is legal in Missouri to blend corn to safe feeding levels if it is to be used for animal feed. The maximum level of aflatoxin that can be fed to livestock is determined by the animal's species and age. Detoxification with anhydrous ammonia is not legal in Missouri.

The information in this article comes from many sources and past articles by Jim Jarman, Agronomy Specialist, (573) 642-0755.

The 2003 Winter Wheat Variety Test information is now on-line. You can either access the information from the http://www.psu.missouri.edu/cropsys/ website or from the Agricultural Electronic Bulletin Board (AgEBB) at: http://agebb.missouri.edu/cropperf/wheat/soft/index.htm. I will announce when the printed versions are available at the Extension Center.

Cole and Boone counties will be hosting beginning Master Gardener Classes starting in late August and early September. Contact those offices or the Callaway County Extension Center for more information.

The Mid-Missouri Grazing Committee is planning an equine conference of late October in Sedalia. More information on the location, program and date will be announced soon.

University of Missouri Extension programs are open to all. 

Still More Drought Issues  August 20, 2003

It seemed like whenever we would switch to writing drought articles it would begin to rain. No such luck so far.

Hot dry weather is a time when spider mites may be seen on soybeans. It may be a fight between the drought and the spider mite, but the mites can be a more serious problem. A very small relative of spiders, they suck sap from plants instead of feeding on insects. There are several pests who feed on soybean leaves. Spider mites are one pest that can cause 100% of leaf loss. The cost of treatment has to be balanced on the yield expected if rains come and the soybeans do not have any leaves.

Look for yellowing spots. Typically, spider mites blow in like dust on the wind. They multiply quickly and spread to adjoining plants. It takes about a week to complete a lifecycle and adults can live just over 2 months. An adult female lays about 100 eggs. These make for a serious, rapidly spreading pest.

Spider mites can be hard to see. They are about 1/60 of an inch long when fully grown. It takes a 10-power magnifier to see them on a leaf. I usually say take a white sheet of paper and shake a few leaves over the paper. If the tiny specks of "dirt" start to move, they are spider mites not dirt. The name spider comes from them spinning a fine web over infested leaves and plants. Webbing may be easier to see than the mites.

Mites can cover a field before the leaf damage is bad enough for total defoliation. Watch for yellowing spots. If yellowing is seen in small circles, check the spots for spider mites. If the mites can be found outside the spots, begin to worry and think about checking their spread. A rain shower will do more than pesticides in cleaning up a spider mite infestation.

Soybean yellowing during hot, dry weather or droughts can also be from charcoal rot. It is a high temperature disease, which begins to grow between 82° and 95° F. The yellowing can typically be tied to thin soils or other droughty areas of a field.

Drought will increase the symptoms and effects of potassium deficiency. Soybean seeds contain much more potassium than corn grain, and soybeans are entering the time of rapid potassium uptake. Early deficiencies appear as yellow margins on older leaves. Browning and death of leaf margins is a symptom of increased deficiency severity.

Making hay or silage from drought damaged soybeans is a common question now. The time to harvest for hay or silage is when half the pods have immature beans. These immature beans dry slowly and mold easily in bails. Dry soybean leaves shatter easily during baling. Silage may be a better answer but soybeans were bred for grain so today’s varieties have poor hay or silage yields. The cost of grain harvest equals about 6 bushels to the acre so combining a 10-bushel per acre yield is actually a better choice than a forage harvest. Silage from soybeans may need to be mixed with corn silage, ground grain or molasses to improve fermentation.

Soybean aphid has been increasing in Missouri. It was found at high enough numbers to treat about a month ago near New London in Ralls County. It is being blown into our state. Soybean aphids are another small insect causing yellow spots in fields. They can be found in small colonies or covering soybean stems and leaves. It has been linked to low potassium fields.

There is lots of drought information at our web site: http://agebb.missouri.edu/drought/index.htm . This article’s information comes from several current Extension drought sources and past articles by Jim Jarman, Agronomy Specialist (573) 642-0755.

The 2003 Winter Wheat Variety Test information is now on-line. You can either access the information from the http://www.psu.missouri.edu/cropsys/ website or from the Agricultural Electronic Bulletin Board (AgEBB) at: http://agebb.missouri.edu/cropperf/wheat/soft/index.htm. I will announce when the printed versions are available at the Extension Center.

Cole and Boone counties will be hosting beginning Master Gardener classes starting in late August and early September. Contact those offices or the Callaway County Extension Center for more information.

A "Cheese-Making Workshop" is set for 8:30 a.m. to 4 p.m., Saturday, Sept. 13, at the Webster County Extension Center on South Highway A (next to City Hall), in Marshfield, Mo. Workshop participants will see demonstrations and receive hands-on practice with the procedures for making Gouda cheese, cream cheeses spiced with various herbs, and yogurt using both goats and cows milk.

The Mid-Missouri Grazing Committee is planning an equine conference on October 28^, 2003, at the Best Western Inn in Sedalia. Some of the topics will be hoof health and micronutrient nutrition for horses, managed intensive grazing (MIG) for equine, do you know good horse hay when you see it, and an expert panel Q and A session. There will be venders and a keynote speaker at lunch. If you need more information, contact the Extension Center, Soil and Water Conservation District or NRCS office near you.

University of Missouri Extension programs are open to all.

Soybean aphids are everywhere, and in large numbers in some fields. The pest originally came from China. Since its arrival, it has been seen in all soybean growing areas in MO. It was found in Callaway County late in 2000, not long after it was first seen in north central U.S. You can read the first information on this pest from the September 17, 2000 newspaper article. Although, Callaway County soybean growers have probably never seen this pest because it has been at very low numbers in fields here and there every year since. This is the first year they are so easy to find and may even infest to numbers needing control.

High numbers requiring spray were found in areas south of Hannibal, Mo., and near Maryville, Mo. In northwest Missouri, they are reporting up to 400 aphids per plant.

The almost invisible pest can build up large colonies quickly. Although there is not yet research on the subject, MU entomologists think an economic threshold for applying controls is 250 aphids per plant. The aphids suck plant juices, weakening the plant, and may spread disease viruses.

In MU caged test plots at Columbia, some soybean plants quickly had thousands of aphids per plant. The pest is so new, we know very little about what it will do under Missouri conditions. Entomologists were surprised that large populations did not develop in the first three years the pest was in the state.

Ben Puttler, extension survey entomologist, has been tracking the pest across the state from the initial locations in northeast Missouri. The soybean aphid was confirmed in the Bootheel region for the first time this August.

The first infestations in the United States were in Wisconsin. The aphids rapidly spread and built up large populations in Minnesota and northern Illinois. They are in Iowa in large numbers this year.

Last year, Puttler confirmed that the aphids were overwintering in the state on their alternative host, an ornamental buckthorn. Initially, we thought that hot weather in Missouri was detrimental to the aphid growth. But, we're disproving that this year, because we have very hot weather and the populations have thrived.

Wayne Bailey, extension entomologist at the University of Missouri, believes large populations of the aphids flew into the state this summer on unusual northern winds that have occurred frequently this year. There are large aphid populations and producers have been spraying in Minnesota, northern Iowa, and northern Illinois. We started finding the winged aphids here after a few days with northern winds.

Bailey said he does not know if the aphids can survive under extreme drought conditions. They attack plants that are most succulent; to get the juices they need to survive. As the plants dry up, the population may dry up. He expects late-planted green and growing soybeans will be the most vulnerable.

Most farmers who have not seen aphids before need to look for them in their fields. At first, they are hard to find. But, if you find colonies of aphids in your fields, they will be the soybean aphids. No other aphids thrive in soybean fields.

You almost have to have a magnifying glass to see them. The almost transparent aphids are light to lime green. The distinguishing features are black eyes and black 'tail pipes' sticking out the other end. Once you know what to look for, they become easy to find. You may also look for shinny spots on the leaves. As the soybean aphid feeds by sucking soybean sap, it gives off drops of honeydew. Scout the upper third of the plant, which is most actively growing, and to look on the underside of leaves.

MU entomologists have seen differences between variety susceptibility to the soybean aphid. They may be more common in fields with potassium deficiencies. If you don't find them in one field, and have another soybean variety planted in another field, you better go check there also. Differences in fine hairs or pubescence on soybean leaves may have something to do with the repelling power of the plant.

The sources of information for this article are Wayne Bailey, Extension Associate Professor of Entomology (573) 864-9905, Ben Puttler, Extension Survey Entomologist, (573) 882-1452 and Jim Jarman, Agronomy Specialist (573) 642-0755. Past news paper articles are available at: http://extension.missouri.edu/callaway/agriculture.shtml.

Current drought information is available from the Callaway County and University of Missouri Extension main web pages at: http://extension.missouri.edu/callaway/ and http://extension.missouri.edu/. Just click on the "New Drought Information" hot link.

A tour of farm shops will be held this evening, August 27^th beginning at Dwayne Schultte’s Quarter S farm shop beginning at 5:30. Two other shops at Larry Deimeke’s and Jim Hale’s shops are included. A meal will be served during the tour.

This is an opportunity to see different types of shops and get ideas on how to make better us of your own farm shop. If you are thinking about modifying or building a shop, this is an opportunity to see different layouts and setups. Contact the Callaway or Audrain County Extension Centers for more information at (573) 642-0755 or (573) 581-3231.

University of Missouri Extension programs are open to all.

Return to the Callaway County Extension Center main page
	Callaway County Extension callawayco@missouri.edu Last update: 12/28/11