By: Andy Michel, Mark Sulc, Curtis Young, CCA, Kelley Tillmon
Potato leafhopper (PLH) adults arrived in Ohio during the last week of June and the first week of July. Since then, the eggs have hatched and we are now seeing late-stage nymphs and adults infesting alfalfa fields. A few fields are showing the typical “hopper burn”, which is a triangular yellowing from the center of the leaf to the leaf margin. The more mature the crop of alfalfa is since the last cutting, the more the hopper burn symptoms will be showing. Hopper burn will also become more pronounced in areas of the state that are short on rain or are predicted to become drier because the alfalfa will not be able to outgrow the feeding activity of PLH. Scouting now and making appropriate management decisions based on the scouting can help avoid serious damage to the crop. Continue reading
Figure 1: Accumulated growing degree days (base 48°F sine calculation method) for January 1- May 2, 2021, at several CFAES Ag Weather System (https://www.oardc.ohio-state.edu/weather1/) locations and additional NOAA stations around Ohio (data courtesy of the Midwestern Regional Climate Center (https://mrcc.illinois.edu).
By Mark Sulc, Aaron Wilson, Kelley Tilmon, Greg LaBarge, CPAg/CCA, Curtis Young, CCA, Andy Michel, Beth Scheckelhoff
Alfalfa fields across Ohio have been observed with alfalfa weevil infestations, some with high numbers and severe feeding damage to the alfalfa.
Accumulation of heat units (growing degree days or GDDs) for alfalfa weevil growth have progressed across Ohio and are now in the 325 to 575 heat unit range indicative of peak larval feeding activity (Figure 1). We are about 2 weeks ahead of GDD weevil accumulation last year.
From the road, severe weevil feeding can look very much like frost injury (Figure 2). Do not be fooled, get out and scout! We have observed very minor frost injury to alfalfa from last week’s cold nights, so if you see “frost injury” in alfalfa, it is more likely to be severe alfalfa weevil feeding damage. For more information on scouting and signs of damage, see the April 20 article in this newsletter: (https://agcrops.osu.edu/newsletter/corn-newsletter/10-2021/alfalfa-weevil-%E2%80%93-it%E2%80%99s-closer-you-think). Continue reading
The best time to take the last harvest of alfalfa and other legumes is sometime in early September in Ohio, for the least risk to the long-term health of the stand. These forages need a fall period of rest to replenish carbohydrate and protein reserves in the taproots that are used for winter survival and regrowth next spring.
Many forage producers around the state have been cutting this past week and are continuing into this week. It will be ideal if this is indeed the last harvest of the season. But some growers might try to squeeze out another late cutting, and others have fields that are not quite ready for harvest right now. Like most farming decisions, there are trade-offs and risk factors to consider when making a fall harvest of forage legumes after the first week of September. This article reviews the best management practices and risk factors affecting fall cutting management. Continue reading
By Mark Sulc
The month of August provides the second window of opportunity for establishing perennial forage stands this year. The primary risk with late summer forage seedings is having sufficient moisture for seed germination and plant establishment, which is a significant risk this summer given the low soil moisture status across many areas.
The decision to plant or not will have to be made for each individual field, considering soil moisture and the rain forecast. Rainfall/soil moisture in the few weeks immediately after seeding is the primary factor affecting successful establishment.
No-till seeding in August is an excellent choice to conserve soil moisture for good germination. Make sure that the field surface is relatively level and smooth if you plan to no-till seed because you will have to live with any field roughness for several years of harvesting operations.
Sclerotinia crown and stem rot is a concern with no-till seedings of alfalfa in late summer and especially where clover has been present in the past. This pathogen causes white mold on alfalfa seedlings and infects plants during cooler rainy spells in late October and November. Early August plantings dramatically improve the alfalfa’s ability to resist the infection. Late August seedlings are very susceptible to this disease, with mid-August plantings being intermediate. Continue reading
Management of potato leafhopper was needed weeks before this hopper burn.
By Christian Krupke and John Obermeyer, Purdue University
Potato leafhopper populations were noticeably higher after last week’s tropical storm remnants blew through, and now the warmer temperature will drive further increases. Potato leafhoppers won’t mind this heat, and alfalfa pest managers should begin sampling their alfalfa shortly after cutting. Continue reading