How Much Does Defoliation Matter?
Let's consider general defoliation of soybeans; this damage can be caused by a suite of insects including bean leaf beetle, Japanese beetle, grasshoppers, and caterpillars. Average accepted economic thresholds for leaf-feeding pests in soybeans are: 25% defoliation during vegetative stages; 15% defoliation for bloom to pod-fill; and 25% pod-fill to maturity. Remember that a synonym for economic threshold is action threshold, meaning that when these levels of defoliation are found it is time to do something to stop that damage. However, late in the season other details need to be considered, particularly the growth stage of plants, the general health of the bean, and the cost of doing something.
A traditional systematic field sampling method is to select 10 plants throughout the field, choosing a trifoliate from the upper, middle and lower canopy on each plant, and repeat this process several times in randomized acres of their field.
This will give you a 30-leaf sample to assess whether feeding is progressing through the canopy or only in the upper canopy. With Taranis SmartScout in-season flights, we are able to remove the man-power of boots on the ground, physical leaf sampling and replace it with a simple and user friendly CONNECT app to cover hundreds of acres in minutes.
Recommended Defoliation Thresholds(*):
- Treat at 30-35% defoliation between emergence and R1 (early bloom)
- Treat at 20% defoliation from R1 through pod filling (R6, full seed)
- After R6 to R6 + 7-10 days, treat if defoliation exceeds 30-35%
- Do not treat after R6 + 7-10 days
A traditional systematic field sampling method is to select 10 plants throughout the field, choosing a trifoliate from the upper, middle and lower canopy on each plant, and repeat this process several times in randomized acres of their field. This will give you a 30-leaf sample to assess whether feeding is progressing through the canopy or only in the upper canopy. With Taranis SmartScout in-season flights, we are able to remove the man-power of boots on the ground, physical leaf sampling and replace it with a simple and user friendly CONNECT app to cover hundreds of acres in minutes.
*
Pro Tip: Reach out to your local consultant and Taranis Customer Success Team Lead to verify area thresholds and actions to be taken with your field!
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