Ontario Grain Farmer March 2021

If a label provides no guidance on re- cropping intervals, sometimes this may indicate that there is no effective herbicide carryover, sometimes it is because there is no data. Typically, this is only an issue with older chemicals. Always use caution on what you are applying and what is being planted afterwards, considering when the application is occurring in the season. BREAKDOWN It is important to understand that herbicide breakdown occurs primarily through two ways; through soil microbes and chemical hydrolysis. Moisture and temperature influence both types of breakdown. Robinson has observed that the amount of rainfall received in the first month after a herbicide is applied, and the soil temperatures after the first month of application show greatest degree of relation between the amount of herbicide carryover. Dry weather for the first month after application increases the chance of carryover. Organic matter and texture can affect breakdown as they bind the herbicide; pH is a bit different and can affect some herbicides one way and others a different way. If a herbicide was applied, and then the crop rotation did need to be changed, Robinson has looked at whether using tillage and/or fall seeded cover crops can help with herbicide breakdown. Both options for a farmer are fairly inexpensive and don’t require a lot of time. Tillage has been found to some degree to reduce the amount of carryover. The hypothesis is that tillage causes some dilution effect, possibly also increasing the amount of degradation that occurs microbially, due to a bump in the microbial population, as long as there is available moisture. If using cover crops to help increase the rate of herbicide, good establishment is key and the cover crop chosen would definitely have to have some tolerance to the herbicide to be useful. Robinson has also considered if manure was added and incorporated. Manure could increase microbial populations to some degree. Dr. Robinson mentioned that some are concerned that adding manure may tie up the herbicide further, but that is all speculative. One thing to keep in mind though, is that the herbicide concentration is already at a very low level, if you have a crop that is already sensitive to such a low level, it is difficult to completely dissipate the risk. The overall take home point is to avoid herbicide carryover — plan and stick to that plan. Laura Ferrier is an agronomist with Grain Farmers of Ontario. l ONTARIO GRAIN FARMER 11 MARCH 2021 Ladybird Beetle (Coccinellidae) Western Bean Cutworm (Striacosta albicosta) Coragen ® knows the difference All bugs are bad? Not when you get to know them. Western bean cutworms, for example, cause major quality and yield damage in corn. Ladybird beetles feed on cutworm eggs and larvae. Because Coragen insecticide knows the difference, it protects your corn from Western bean cutworm at all life stages and leaves helpful beneficials alone. Group 28 Coragen insecticide has excellent tank-mixability, can be applied any time during the day and gives you 7 to 21 days of extended control. Think of it as nature and science working together. Always read and follow label instructions. Member of CropLife Canada. FMC, the FMC logo and Coragen are trademarks of FMC Corporation or an affiliate. ©2021 FMC Corporation. All rights reserved. 74008 - 01/21 Profitable Crop Production (Agriculturae pecuniam maximus) This article is based on information provided during a session of the Ontario Agricultural Conference. Grain Farmers of Ontario was a sponsor of this conference