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In parts of central Alberta, lygus counts continue to exceed thresholds significantly (with counts as high as 450 lygus in 10 sweeps in some fields). In other areas, lygus numbers are just at or approaching threshold but the crop is very near to swathing. With these counts, growers are encouraged to resist the urge to simply spray and to be…
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Scouting for bertha armyworm can be tricky when scouting during the heat of the day. Click here to view a short scouting video with Canola Council Agronomist Tiffany Martinka. It……
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On hot days, bertha armyworms take shelter low in the canopy or on the ground under leaf litter. This is not a good time to scout or spray. Bertha armyworms feed more actively on cooler days and in evenings. This is the time to spray. When scouting, include all worms larger than half an inch long in threshold counts. Smaller…
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When sweep netting for lygus (shown above), it may seem that there are more lygus in the field than end up in the sweep net. This is expected. Sweep net thresholds were establishing knowing that lygus in the sweep nets represented only a certain percentage of lygus in the canopy. Stick to the thresholds, and follow sweep net techniques outlined…
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Second generation lygus have arrived. Young nymphs will reach late instar and adult stages in 5 to 14 days. When scouting to see if lygus numbers are near thresholds, include later instars — the ones with black dots on their back — as well as adults in the count. Bertha armyworm larvae are starting to feed in some locations…
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Some fields may have a variety of green worms feeding, including bertha armyworm, diamondback moth larvae, imported cabbageworm and alfalfa looper. Here's how to tell them apart…
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We don’t have scientific evidence to combine thresholds, but where an “additive” effect of multiple species can make sense is when more than one species are feeding on key yield-producing areas — flowers, buds or pods — at the same time…
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Lygus, bertha armyworm and diamondback moth have a number of natural enemies that will keep populations in check. These beneficial insects may not control an immediate insect threat — growers will still have to spray if economic thresholds are reached — but beneficials can keep a lid on populations. The key to preserving beneficial insects is to follow thresholds and…
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Include nymphs (shown above) when doing lygus sweep net counts. Bertha risk rising. Zebra caterpillers are usually confined to small areas within a field. (Photo source: Roy Ellis)…
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