Corn herbicide performance examined
By
John Grimes-
By the end of last week, farmers had experienced an approximately 10-day run of favorable weather that has allowed them to make a great deal of progress towards completing spring field work. The corn percentage planted thus far is well ahead of schedule and I’m also aware of a few acres of soybeans planted in the area. Let’s hope the weather in the coming weeks allows farmers to take full advantage of this early planting window.
Reminders about dry
weather, preemergence
corn herbicide performance
We recently experienced a dry weather period that has enabled an early and rapid start to corn and soybean planting. Our concern in this type of situation is that continued dry weather can result in at least partial failure of preemergence herbicides, which are currently being applied at a rapid rate also. In a typical spring planting season, we receive rain often enough to ensure preemergence herbicide effectiveness, and it’s possible that the rain forecast for the end of the week will ensure that it occurs this year also. Preemergence herbicides reach maximum effectiveness only if rain moves them down into soil before weed shoots emerge. Once the shoots have emerged, herbicides that act strictly through residual activity have lost most of their effectiveness, unless you are a big believer in “reachback activity.”
In a situation where it is dry for the first several weeks after planting, we assume a subsequent rain will eventually “activate” preemergence herbicides, so that they will provide weed control, even if they fail to control the weeds that emerge soon after planting. One solution here is to apply a low rate of glyphosate or other postemergence herbicides to control the small weeds that emerge initially, with the hope that the preemergence herbicides will control the later-emerging weeds.
It may be worth reconsidering an application of preemergence herbicides when there is no rain in the foreseeable (week or more) forecast, and switching to an early postemergence application. An early postemergence application of foliar plus residual herbicides can be just as effective at preventing yield loss due to weed interference, compared with a program of consisting sequential applications of preemergence and postemergence herbicides.
Most preemergence corn herbicides can be applied to emerged corn, and some of them have enough foliar activity to control small, emerged weeds without the need to add postemergence herbicides.
Carpenter bees
I have received several inquiries over the past several days regarding large bees buzzing past people’s heads near decks, playground equipment, garages, and plant arbors. These are most likely male carpenter bees performing their annual aerial antics as they attempt to drive off other male bees. Carpenter bees look very similar to bumblebees except their abdomen is an iridescent blue instead of being covered with black or yellow hair. Each spring, the newly emerged males and females begin the characteristic behavior that, if not understood, seems terrifying.
While the females are busily collecting pollen and nectar wads to shove into their wood tunnels to feed their progeny, the males buzz back and forth around the area guarding their territory from other males.
The males may appear to be menacing; however, they lack stingers (a.k.a. ovipositors). As they move around a person’s head they are not trying to sting or intimidate; instead, they are trying to determine how to maneuver around this new, moving object!
Although carpenter bees are excellent pollinators, the females can cause extensive damage to exposed horizontal wood, particularly boards made from pine or cedar. They drill holes measuring almost 1/2” in diameter vertically into the wood, and then they tunnel horizontally to construct larval chambers.
A chemical treatment using an appropriately labeled insecticide can protect wood for short periods, especially in the spring and summer when carpenter bee nesting activity is apparent. Dust formulations typically provide residual effects and are effective due to the nature of carpenter bee gallery construction. Precisely inject the dust directly into each nest entrance hole and as deep into the tunnel as possible and also apply it to the adjacent wood surface. Newly emerged bees also will contact the dust when attempting to leave their gallery. Dusts containing bendiocarb, boric acid, carbaryl, chlorpyrifos, cyfluthrin, and pyrethrin are labeled for carpenter bee control.
The best strategy is to plug the holes with steel wool, caulk the holes, and then paint the wood with at least two coats of an acrylic paint. However, the holes should not be plugged until fall. Closing the “door” now with the bees inside their chambers will only result in more damage as the bees chew lateral holes to free themselves.
Lawn management
Higher temperatures, adequate soil moisture and longer days can only mean one thing; the race for the perfect lawn is on. As consumers and professionals gear up for months of mowing, they should take the time to start off on the right foot.
First, if the lawn has not had its soil tested in several years, send off a soil sample for testing now. It is impossible to adequately judge the nutritional needs of turf by visual inspection. Thin or declining turf may be an indicator of other problems and applying more fertilizer is not always the correct solution.
Second, be sure to adequately service the lawnmower before the height of the mowing season: Make sure blades are sharp and balanced; clean the underside of the mowing deck; properly service the engine and adjust the height of the cut to around 2 1/2-3” (a good height for strong, healthy turf). A properly maintained mower will leave a cleaner cut on the leaf blade and be less likely to bog down when faced with fast growing thick turf.
Third, mow as needed rather than by the calendar. One should only remove one-third of the leaf blade at a time. Cutting off more than one-third weakens the grass plant and stresses the turf. Maintaining a good height in the spring may require cutting as frequently as two or three times per week. Also, don’t let wet weather get in the way of mowing; it is better to mow wet grass than to try to cut grass that has gotten out of hand.
Finally, as the season progresses, damaged or dead areas will become more apparent. Repair them early in the season while moisture is readily available. Prepare the area by loosening up the soil and raking in turf seed.
Be sure to select the same or similar turf seed as the original lawn. Planting a different type of grass can lead to a patchwork look to the lawn. Do not apply pre-emergent herbicides to newly seeded areas. They will inhibit germination of turf as easily as they do weed seed.
John Grimes is the Ohio State University Extension Educator for Agriculture and Natural Resources in Highland County.[[In-content Ad]]
Reminders about dry
weather, preemergence
corn herbicide performance
We recently experienced a dry weather period that has enabled an early and rapid start to corn and soybean planting. Our concern in this type of situation is that continued dry weather can result in at least partial failure of preemergence herbicides, which are currently being applied at a rapid rate also. In a typical spring planting season, we receive rain often enough to ensure preemergence herbicide effectiveness, and it’s possible that the rain forecast for the end of the week will ensure that it occurs this year also. Preemergence herbicides reach maximum effectiveness only if rain moves them down into soil before weed shoots emerge. Once the shoots have emerged, herbicides that act strictly through residual activity have lost most of their effectiveness, unless you are a big believer in “reachback activity.”
In a situation where it is dry for the first several weeks after planting, we assume a subsequent rain will eventually “activate” preemergence herbicides, so that they will provide weed control, even if they fail to control the weeds that emerge soon after planting. One solution here is to apply a low rate of glyphosate or other postemergence herbicides to control the small weeds that emerge initially, with the hope that the preemergence herbicides will control the later-emerging weeds.
It may be worth reconsidering an application of preemergence herbicides when there is no rain in the foreseeable (week or more) forecast, and switching to an early postemergence application. An early postemergence application of foliar plus residual herbicides can be just as effective at preventing yield loss due to weed interference, compared with a program of consisting sequential applications of preemergence and postemergence herbicides.
Most preemergence corn herbicides can be applied to emerged corn, and some of them have enough foliar activity to control small, emerged weeds without the need to add postemergence herbicides.
Carpenter bees
I have received several inquiries over the past several days regarding large bees buzzing past people’s heads near decks, playground equipment, garages, and plant arbors. These are most likely male carpenter bees performing their annual aerial antics as they attempt to drive off other male bees. Carpenter bees look very similar to bumblebees except their abdomen is an iridescent blue instead of being covered with black or yellow hair. Each spring, the newly emerged males and females begin the characteristic behavior that, if not understood, seems terrifying.
While the females are busily collecting pollen and nectar wads to shove into their wood tunnels to feed their progeny, the males buzz back and forth around the area guarding their territory from other males.
The males may appear to be menacing; however, they lack stingers (a.k.a. ovipositors). As they move around a person’s head they are not trying to sting or intimidate; instead, they are trying to determine how to maneuver around this new, moving object!
Although carpenter bees are excellent pollinators, the females can cause extensive damage to exposed horizontal wood, particularly boards made from pine or cedar. They drill holes measuring almost 1/2” in diameter vertically into the wood, and then they tunnel horizontally to construct larval chambers.
A chemical treatment using an appropriately labeled insecticide can protect wood for short periods, especially in the spring and summer when carpenter bee nesting activity is apparent. Dust formulations typically provide residual effects and are effective due to the nature of carpenter bee gallery construction. Precisely inject the dust directly into each nest entrance hole and as deep into the tunnel as possible and also apply it to the adjacent wood surface. Newly emerged bees also will contact the dust when attempting to leave their gallery. Dusts containing bendiocarb, boric acid, carbaryl, chlorpyrifos, cyfluthrin, and pyrethrin are labeled for carpenter bee control.
The best strategy is to plug the holes with steel wool, caulk the holes, and then paint the wood with at least two coats of an acrylic paint. However, the holes should not be plugged until fall. Closing the “door” now with the bees inside their chambers will only result in more damage as the bees chew lateral holes to free themselves.
Lawn management
Higher temperatures, adequate soil moisture and longer days can only mean one thing; the race for the perfect lawn is on. As consumers and professionals gear up for months of mowing, they should take the time to start off on the right foot.
First, if the lawn has not had its soil tested in several years, send off a soil sample for testing now. It is impossible to adequately judge the nutritional needs of turf by visual inspection. Thin or declining turf may be an indicator of other problems and applying more fertilizer is not always the correct solution.
Second, be sure to adequately service the lawnmower before the height of the mowing season: Make sure blades are sharp and balanced; clean the underside of the mowing deck; properly service the engine and adjust the height of the cut to around 2 1/2-3” (a good height for strong, healthy turf). A properly maintained mower will leave a cleaner cut on the leaf blade and be less likely to bog down when faced with fast growing thick turf.
Third, mow as needed rather than by the calendar. One should only remove one-third of the leaf blade at a time. Cutting off more than one-third weakens the grass plant and stresses the turf. Maintaining a good height in the spring may require cutting as frequently as two or three times per week. Also, don’t let wet weather get in the way of mowing; it is better to mow wet grass than to try to cut grass that has gotten out of hand.
Finally, as the season progresses, damaged or dead areas will become more apparent. Repair them early in the season while moisture is readily available. Prepare the area by loosening up the soil and raking in turf seed.
Be sure to select the same or similar turf seed as the original lawn. Planting a different type of grass can lead to a patchwork look to the lawn. Do not apply pre-emergent herbicides to newly seeded areas. They will inhibit germination of turf as easily as they do weed seed.
John Grimes is the Ohio State University Extension Educator for Agriculture and Natural Resources in Highland County.[[In-content Ad]]