Will ergot be a problem for us in the 2000-growing season? If so, what should we do to minimize the risk? What should we do in our direct seeding systems? Ergot affected many farms across Saskatchewan in 1999. For many producers this is the first time their wheat (primarily) has been downgraded because of high ergot levels.
Ergot attacks cereals and both wild and cultivated grasses throughout the world. The disease is caused by numerous species of fungi in the genus Claviceps, with the most common and damaging one being Claviceps purpurea. Ergot affects only the flowering parts and the developing kernels. It is common in rye, but it can occur in wheat and barley. Oats are rarely affected. Recent outbreaks have occurred on the open-floreted, male-sterile wheat lines that are used to produce hybrid seed. However there is no data available that indicates certain wheat varieties grown on the prairies are either more or less susceptible than other wheat varieties. The bottom line: there are no resistant varieties.
The variety AC Barrie has been singled out as being extremely susceptible to this disease. However for virtually every HRSW variety one can find a producer somewhere in Saskatchewan who was affected by ergot. The key factor to remember is that in 1999, 50.9 % of the HRSW seeded acres in Saskatchewan were AC Barrie (CWB 1999 variety survey). Varieties such as CDC Teal, Katepwa, and Columbus accounted for only 26.9 % of the seeded acres combined. Therefore it is important to remember that the main reason we hear significant commentary regarding AC Barrie and ergot is because 1 in 2 fields were seeded to this variety.
So why was 1999 so bad? The short answer is that we had a cool wet spring and early summer followed by wet conditions during flowering in many areas. Wet, cool weather prolongs the flowering period thereby extending the infection period. Any other agronomic factors, such as herbicide injuries, which delay maturity or cause more open-floret physiology, would also favor ergot.
The disease begins in the spring from ergot bodies, which are present in the field from a previous cereal crop, or from grasses in ditches and along field boundaries. The first sign of ergot infection occurs at or soon after flowering. The infected florets exude a sugary substance referred to as honeydew. The honeydew contains a large number of asexual spores called conidia. Because the honeydew has a rotten-smelling odor a large number of flies and other insects are attracted to the infected heads. The insects become contaminated with conidia and inadvertently spread the disease to other healthy flowers. Rain splash and wind can also carry the conidia to other florets. New infections occur as long as flowering occurs. The purplish-black ergot body develops in place of the kernels.
So what can we do about it? For grain produced in 1999 grain cleaning is an option. Though this is an added cost, the cleaning process can often improve the grade significantly. For the 2000-growing season there are a number of practices which can be implemented:
So there you have it, ergot in a nutshell. The potential for an outbreak in 2000 similar to 1999 is unlikely. But if the spring is wet again the possibility does exist. However if we implement some strategies for 2000 we can minimize the outbreak.
Tim's tidbits on ergot:
In the past ergot found in rye was often more valuable than the grain itself. Pharmaceutical companies used alkaloid compounds found in the ergot in medicines. They have served an important role in stopping bleeding and in the postpartitive contraction of the uterus just after childbirth. It has also been used in the treatment of migraine. However, today most of these derivatives are made from synthetic forms of the alkaloids. Ergotism is a symptom that occurs after humans or animals eat food with high levels of ergot contamination.
Ergotism has been responsible for many deaths throughout history. Various epidemics have occurred, for example in Spartan in 2430 BC, and in Europe in both 857 and 943 AD.Disease symptoms that appear several hours after ingestion include a burning sensation and twitching of the extremities known as St. Anthony's Fire. Thirst becomes extreme, followed by cramping of the abdomen, vomiting, and diarrhea and twitching proceeds to convulsions. The pulse becomes weak and if the patient survives, limbs may become affected by gangrene because of constriction of the capillary beds. The extent of the symptoms is dependent on the amount of ergot ingested. As little as one ergot body in 1000 kernels can be considered unsafe.