Checking Your Fields Now Can Help Avoid Issues Next Spring
By Shannon Friesen, PAg Crops Extension Specialist, Moose Jaw
Harvest is a great time to get out into the field to scout for late season diseases and crop damage. By monitoring and identifying issues that are found in the field now, you can gain a better understanding of potential issues in the future.
Before entering a field, ensure that you have all the tools you will need for proper scouting, including a trowel, clippers, sample bags, a hand lens and a camera. It is also a good idea to minimize the spread of soil from field to field to reduce your risk of spreading diseases such as clubroot. This can easily be done by wearing disposable boot covers between fields, parking away from the field entrance and knocking soil off equipment and vehicles. When scouting a field, there are several different patterns that can be followed, depending on what pest you are looking for. These patterns can include scouting random areas of the field in a W pattern, scouting specific areas like low spots or scouting along field edges and ditches.
Summer and into fall is also a good time to determine whether or not you have herbicide resistance on the farm. Look for patches or patterns in the field where the weeds escaped herbicide application and are now setting seed. If you are unsure why the weeds may not have died, take samples of the mature seed and send them away to the Crop Protection Lab in Regina for confirmation. A herbicide resistance management plan can then be formed for future years. This management plan should include integrated pest management techniques and focus on practical solutions such as crop rotation and layering herbicides.
As crops dry down it also becomes easier to see patterns in the field that may indicate a disease issue. In the case of canola, scouting prior to swathing can reveal if there are any patches of lodged or pre-maturely ripening plants that may be indicative of a disease such as blackleg, sclerotinia or even clubroot. Pull plants in various parts of the field and check the roots, stems, leaves and pods. Sclerotinia will infect stems and leave them hollow and bleached. Often you will be able to find sclerotia, or small black hard bodies, inside the stem that will eventually fall to the soil and overwinter. Broadleaf crops such as mustard, peas, lentils and sunflowers are also susceptible to sclerotinia infection so rotations should include cereal crops to help break up the disease cycle.
Blackleg can be easily identified by pulling poor looking canola plants and looking for lesions at the bottom and middle areas of the stem. To check for blackleg infection, use clean and sharp clippers to slice through the stem. Your yield has likely been reduced if you see significant amounts of blackened stem. If so, you may want to consider switching to a variety that has a different resistance gene.
Clubroot symptoms in the field include wilting, pre-mature ripening and the presence of galls on the roots. Check patches in the field that do not look normal and pull up any plants that you are suspicious of, especially near field entrances and in low spots. If you suspect that clubroot is in a field, contact your local crops extension specialist as soon as possible to make a management plan.
Cereal crops infected with diseases like fusarium head blight are distinguishable by their bleached heads and un-filled kernels. If the infection is severe enough in the plant, the kernels may be shrunken with a chalky white appearance. Fusarium head blight can be properly managed with crop rotation, resistant varieties, proper fungicide timing and using seed with low disease levels and high germination and vigour.
Pulse crops like peas and lentils are often affected by root rots, including Aphanomyces, that can reduce yields, if severe enough. Look for pre-maturely yellowing crops that are stunted and have not advanced normally — often these plants can be found in wet or low spots or in compacted areas of the field. Aphanomyces can be managed by cycling out of pulse crops for a minimum of six years (preferably eight years) and using good agronomics such as selecting fields that drain well and practicing proper fertility and inoculation.
Harvest also presents an opportunity to check for insect damage. Scouting for insects such as flea beetles and grasshoppers near field edges is a good way to determine what possible issues you might have next year and what crops should be grown in rotation. Look for damage on roots, pods, leaves and kernels to determine if it was made by an insect that is of economical concern. Check forecast maps and develop a management plan if pressures were high this year. This management plan should focus on integrated pest management techniques, including using resistant varieties, considering economic thresholds and promoting beneficial insects.
By taking the time now to scout your fields, you will gain a better understanding of what’s happening in the field and how best to manage it next year.
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