Weather update: Soybean water stress, poisonous trees
Hopefully by the time you read this, we will have received some much needed rainfall. The National Weather Service is saying that most places will get some rain within this next few weeks. They are saying that it will not end the drought at this time and the worst hit areas of northwest Ohio may get the least rainfall where it is needed most.
Symptoms of Water Stress on Soybeans
Because of the drought conditions and high temperatures, soybeans are exhibiting symptoms of water stress. According to Laura Lindsey, Ohio State University Extension’s soybean and small grains specialist, the dry weather is causing flipped leaves, which expose a silver-green underside, reflecting light. In more severe cases, the outer leaves of the trifoliate will close together to reduce the leaf area exposed to sunlight and reduce water loss. Water-stressed soybeans will grow slower and have smaller leaves compared to soybeans growing with adequate soil moisture.
Lindsey said that soybean yield potential is influenced by total number of pods per plant, number of beans per pod and seed size. Stress conditions during soybean reproduction can reduce yield by affecting one or more of these yield components. Vegetative growth, flowering, pod development and seed filling stages overlap allowing the plant to compensate for short periods of stress. Many soybeans are beginning to flower around the county. In a normal year, 60 to 75 percent of soybean flowers will abort, but this number can increase in a stressful year. Lindsey also says that flowering can occur through the beginning of the R5 growth stage (beginning seed). If water stress is alleviated prior to the R5 growth stage, some flowers and pods can still be produced compensating for the flowers that were aborted earlier. If water stress persists, soybean yield will be reduced, especially as plants enter the R4 growth stage (full pod). Yield reductions at this time result mainly from reductions in total pod number per plant. “At the R6 growth stage, water stress will cause a reduction in seed size,” Lindsey said.
Poisonous Trees and Livestock
With the recent storms downing a lot of trees, we now have two components that cause the threat of livestock poisoning. Poisoning is most common when grazing is scarce, such as periods of dry weather like we have seen this summer. With the scarce pasture, vegetation animals will graze plants that they don’t normally eat or trees that may have come down in the pasture. Clif Little, OSU Extension Educator in Guernsey and Noble counties put together a good summery of potential problems with poisonous trees. Below are some symptoms and trees that Little encourages you to watch for as you inspect your livestock and pastures.
Among the most deadly this time of year is the wild black cherry. The leaves and twigs of fallen wild black cherry trees are readily eaten by livestock and are potentially deadly. The seeds, twigs, bark and leaves of the wild black cherry contain a highly toxic compound, hydrocyanic acid. Poisonings most often occur when wilted leaves are eaten, but can also occur when leaves are consumed fresh or dry. Cyanide poisoning causes a deficiency of oxygen reaching the body tissues. Symptoms following consumption appear quickly. Animals may exhibit excitement, incoordination, convulsions, rapid and labored breathing. Consult your veterinarian immediately if you suspect poisoning. Wild black cherry trees should be among the first to be removed from livestock grazing lands.
Red maple poisoning can result from livestock consuming wilted leaves of fallen trees. Dried leaves have been reported to remain toxic for up to 30 days. The cause of toxicity is not clearly understood however, the primary effects are acute hemolytic anemia, methemoglobinemia and Heinz body formation in the red blood cells. Symptoms develop three to four days after ingestion and may include rapid breathing and heart rate, weakness, depression, cyanosis and brownish discoloration of blood and urine.
The black locust tree contains several toxic compounds found in the sprouts, leaves, bark, flowers and seed pods including a glycoside (robitin) and phytotoxins (robin and phasin). Affected animals may exhibit signs of depression, diarrhea, weakness, posterior paralysis, pupil dilation, weak pulse and rapid, irregular heartbeat.
Many oak species contain toxic tannins. Large quantities of young leaves, sprouts and green acorns are toxic. Livestock must consume large quantities of these plant parts for a period of time before poisoning will occur. These plant tannins or their metabolites may cause intestinal and renal dysfunction. Symptoms appear several days after the period of consumption and include abdominal pain, depression, diarrhea and blood in urine.
Our state tree the buckeye tree can and does make cattle sick each year. Cattle readily consume fallen buckeyes. Toxicity is attributed to glycosides and possibly alkaloids. Sprouts and leaves may also be poisonous. Animals exhibit depression, incoordination, twitching, paralysis and inflammation of mucous membranes. If caught quickly, treated animals usually survive.
As we clean up from the storm, some people mistakenly throw branches and clippings in to pastures. One of the most deadly shrubs to livestock is the yew. Yews are flat-needled evergreen shrubs with a bright red fleshy cup-shaped berry. The leaves, bark and seeds contain alkaloids that affect the nervous system and are toxic green or dry. Poisonings often occur when clippings are accessible to livestock. Symptoms include gaseous distress, tremors, diarrhea, convulsions, dilated pupils, weakness and respiratory difficulty.
This combination of summer drought with high winds and broken trees has created a perfect storm for livestock poisoning. Clean pastures and hay fields of these potentially harmful trees. Little also suggests that you provide additional feed and/or hay when forage grazing is limited and as always, consult your veterinarian if you suspect poisoning.