Wednesday, October 20, 2010

Resistance to Strobiliurin Fungicides

Today (20 October), a report out of the University of Illinois confirmed that a field in Tennessee where frogeye leaf spot was found and sprayed twice with a strobilurin fungicide but still had high levels of the disease was because the pathogen that causes the disease (Cercospora sojina) was resistant to the fungicide. This finding was based on laboratory assays that examined the sensitivity of the isolate obtained from the field in Tennessee with baseline isolates and compared against active ingredients like azoyxstrobin, pyraclostrobin, and trifloxystrobin. These are the active ingredients that are found in fungicides such as Quadris, Headline, and Stratego.

What does this mean for Wisconsin? Most importantly, this serves as a very important reminder that the use of fungicides should be done based on several factors, including knowledge of the variety planted and if there is resistance to the targeted diseases of interest, followed by active scouting during the growing season to assess if conditions would warrant a fungicide application. Misuse or overuse of a foliar fungicide can increase the risk for resistance. Specifically for frogeye leaf spot in 2010, we did see symptoms in many fields, but severity was low on average. However, this is the sort of information that should be used to build a working knowledge of the specific diseases that may affect production fields in order to most effectively build a long-term management program.

Based on our data from Wisconsin over the past several years, in the majority of situations a foliar fungicide was not found to be needed and would have been an additional cost to production.

Combine and Tractor Fires . . . A Burning Problem

Combine and tractor fires cause over $20 million in property losses each year and millions more because of lost time and downed crops during the busy harvest season. Fires not only cause huge losses and waste time . . . they also cause 40 or 50 serious injuries each year, and occasionally a person is killed because of a farm machinery fire. As we move into harvest remember there are two keys to preventing series machinery or life loss.

  1. Prevention
  2. Preparation in case a fire does break out.

Machinery Fire Prevention

For a fire to occur, three things must be present: air, a material to burn, and a heat source. Since it is impossible to eliminate air around a farm machine we must focus on keeping the machine clean of possible fire-causing materials and eliminating all possible sources of heat that could lead to a fire.

Cleanliness and Maintenance

Begin every harvest season with a clean machine. Pay special attention to the engine and engine compartment, since about 75% of all machinery fires start in that area. Use a pressure washer to remove all caked-on grease, oil, and crop residue. A clean engine will run cooler, operate more efficiently, and greatly reduce your chance for fire.After starting the season, make sure you frequently blow any dry chaff, leaves, and other material off the machine with compressed air. Also, clear off any wrapped plant materials on bearings, belts, and other moving parts.Pay close attention to your machine operator's manual and follow all instructions and schedules for lubrication and routine maintenance. If you notice any leaking fuel or oil hoses, fittings, or metal lines, make sure to replace or repair them immediately!

Eliminate Heat Sources

Combine and tractor fires can be caused by several heat sources. The most common is exhaust system surfaces that contact any flammable material. Make sure your exhaust system including the manifold, muffler, and turbocharger are in good condition and free of leaks.When checking your oil and performing other daily maintenance, quickly scan any exposed electrical wiring for damage or signs of deterioration. Replace any worn or malfunctioning electrical component with proper parts from your dealer. If you are blowing fuses, or have a circuit that intermittently cuts out, it's a good sign that there's a short or loose connection in the system. The arcing electrical wires on a farm machine will generate extremely high temperatures.Also keep an eye out for worn bearings, belts, and chains. A badly worn bearing can glow red-hot. Any rubber belt subjected to intense heat from a worn part can burst into flames.

Being Prepared

Despite your best intentions and good maintenance, a fire on a tractor or combine can still occur. Your best source of protection for a combine is at least one fully charged ten-pound ABC dry chemical fire extinguisher. A five-pound unit is recommended for tractors. Select only extinguishers with an Underwriter's Laboratory approval. Having two extinguishers on the machine is even better in case one malfunctions or loses pressure. Keep one mounted in the cab, and one where it can be reached from the ground.Check your extinguishers periodically, paying special attention to the pressure gauge. To function effectively, the gauge must show adequate pressure to expel the powder inside.Extinguishers should also be checked periodically by someone from your local fire department or insurance company. Any extinguisher that has been even partially discharged must be fully recharged before it's used again. During even a brief discharge, the tiny dry chemical particles will create a small gap in the internal seal of the extinguisher valve. This tiny opening will cause any remaining pressure to leak out in a few hours or days.

What If I Have A Fire?

If a fire does break out on a machine you're operating, quickly shut off the engine, grab your extinguisher, get out, and get help. If you forget to grab the extinguisher, don't go back in after it unless the fire is extremely small or confined to an area well away from the cab.Having a cellular phone or two-way radio nearby will help get professional assistance to the field more quickly.Approach any fire with extreme caution. Even a small fire can flare up dramatically as you open doors, hatches, or other areas to gain access. These types of fires are especially dangerous when liquid fuels are involved. If possible, use the extinguisher's flexible hose to shoot the chemical from a safe distance at the base of any flames you see. Continue to blanket flames to allow the fire to cool and prevent a reflash. Remember that it may not be possible to put out every fire. If it is in a difficult-to-reach area or seems out of control DON"T RISK the chance of injury or even DEATH....wait for help to arrive.

Post Authored by John Shutske at