In the Midwest and Eastern US, PLH are considered the most damaging insect pest to alfalfa yield and quality. PLH damage can lead to stunting, lower yields, reduced crude protein content, loss of forage palatability, and loss of stand density.
Here's some general information on PLH damage and management.
General Information
PLH control is generally needed during July and August in the Midwest and Eastern U.S.
Hot growing conditions can cause PLH populations to increase very quickly.
Pay special attention to new seedings and 3rd crop regrowth.
Threshold: 1 adult in 10 sweeps. Adults at threshold are an indication deadly immatures are not far behind. Immatures (nymphs) are the most damaging stage of PLH.
Do not spray stubble for PLH control; wait for 3-4 inches regrowth or about 5-6 days to entice PLH back into fields.
PLH can cause severe damage to alfalfa plants before the yellow “burn” appears on leaves; Use a sweep net to detect PLH before symptoms appear. Once symptoms appear, damage is already done.
Damage:
PLH causes a yellow V-shaped “hopper burn” pattern on leaves. Cell sap is extracted from plants, damaging the plant’s plumbing system (phloem and xylem), restricting water and nutrient flow.
“Hopper burn” is a result from the PLH injecting a toxin during nutrient extraction. Once the classic yellow Vshaped pattern appears, the damage is done. Purple coloration often occurs as plant sugars produced in leaves are unable to be processed normally.
Stunted plants will have reduced root growth, water usage and weeds can often gain advantage.
Reduces yield potential; yield losses up to 0.5 DM Ton/acre per cutting or more.
Reduces quality and crude protein, increases nondigestible NDF fiber levels resulting in reduced forage intakes and palatability.
Weakens alfalfa plant health allowing for other foliar diseases and stress to alfalfa.
New seedings are especially susceptible to PLH damage and can result in yield
CROPLAN Forage Specialist Jeff Jackson provides more information on potato leafhoppers in alfalfa in this video:
Contact your local Premier agronomist for more information on PLH management.
By the time this update reaches you, we will have wrapped up the first month of our new fiscal year and will be under way with our external financial audit for the year completed on September 30. While unofficial, I can safely report that 2025 will be a solid year with slight increase in total sales and strong bottom line performance. I look forward to sharing the results and more with you next month.
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