Insect Pests Continue To Attack Hemp

CBD hemp harvest is underway for some growers, while others expect to harvest all the way into October. After a stressful growing season, growers are looking forward to a (hopefully) successful harvest. Because there are still plants in the field, pest attacks still loom, and some growers are seeing late-season damage first hand. As of Wednesday afternoon, growers in Jackson county have reported extensive damage to the flowering portion of their CBD plants caused by corn earworm (Fig. 1, 2). Unfortunately, there are no chemical control options at this point, but by documenting damage and the pests causing it, we can start developing recommendations for the coming years.

 

Fig. 1 Corn earworm larva feeding on CBD hemp plant.

Fig. 1.  Corn earworm larva feeding on CBD hemp plant.

 

Fig. 2 Damage caused by corn earworm.

Fig. 2.  Damage caused by corn earworm.

 

One management option for some pests may be cultivar selection. Hemp growers purchased seeds from different companies across the county and there are around 16 different cultivars currently grown across Indiana. However, some of the cultivars that growers selected seem to be more susceptible to pathogens and insects. One of the susceptible cultivars is the Midwest Strain from Jupiter Seed. This cultivar seems to be attractive to potato leafhopper (Fig. 3). Whole plants of this cultivar are exhibiting the characteristic hopper burn and have multiple nymphs crawling on leaves. Because we do not have the option to spray insecticides at this point, selecting resistant cultivars is going to be an important management strategy.

 

Fig. 3 CBD plant with hopper burn, notice the potato leafhopper nymph circled in the photo.

Fig. 3.  CBD plant with hopper burn, notice the potato leafhopper nymph circled in the photo.

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