Posts

Visit the Morrow County Master Gardener Volunteers to get your garden questions answered at Eco – Center Earth Day event.

• Fruit Tree Planting Tips
• Updates on Chlorpyrifos
• Tips for tuning up your sprayer
• Woolly apple aphid identification and management
• Best practices for planting strawberries

https://u.osu.edu/fruitpathology/fruit-news-2/

A new factsheet on “Avian Influenza Detected in Dairy Cattle” has been developed and posted on the front page of our web site:  https://dairy.osu.edu/

Alfalfa weevils are one of the two key alfalfa pests in Ohio and now is the time to brush up on the scouting procedure and to add reminders to scout onto your calendar. Alfalfa weevil adults (and some eggs) overwinter in Ohio and lay eggs and become active when temperatures exceed 48°F. The larval stages of alfalfa weevil cause the most damage through foliar feeding, particularly during the 3^rd and 4^th instars. Peak larval activity and feeding damage are at their highest when heat units for the area are between 325 and 575 (accumulation from a base of starting at 48°F January 1^st). As of writing this (Jan. 1 – March 31 ), heat units range from 270 in southwest Ohio to 118 in northeast Ohio. In terms of growing degree days, southern Ohio is comparable to this time last year but northern Ohio is ahead of schedule.

Figure 1. Map of accumulated growing degree days (base 48°F sine calculation method) for January 1 – March 31, 2024 at CFAES Ag Weather stations across the state (https://weather.cfaes.osu.edu//) and additional NOAA stations around Ohio (Midwestern Regional Climate Center (https://www.mrcc.purdue.edu))

Even if you’re in an area that hasn’t accumulated many heat units yet, don’t put off scouting. The unusually warm temperature early this March put us ahead of schedule historically, even with the dip in temperatures that followed. Early patches of warm weather can jump-start alfalfa weevil development; while the following cold stretch will slow alfalfa growth. In the past years, this scenario has resulted in situations where fields become heavily infested, and the action threshold is met.

A video about scouting alfalfa weevils can be found here: https://forages.osu.edu/video

An initial assessment of whether a field may have an alfalfa weevil problem can be made by assessing tip and foliar feeding. Alfalfa weevil damage is characterized by small pinhole feeding starting from the tip of the plant. From a distance, heavy damage can look white or frosty in appearance. Older stands of alfalfa are favorable for alfalfa weevil due to previous populations having the opportunity to overwinter nearby.

To confirm whether or not a field has an alfalfa weevil concern, scouting is key. To scout for alfalfa weevil collect 10 stem samples randomly from various areas of the field. Be sure to pick or cut the stem samples off at ground level and place them upside down in a bucket. When all samples are collected vigorously shake the samples in the bucket. Shaking will knock loose the larger more developed larvae. Once shaken inspect the tips of each sample for early-stage larvae. Count the larvae found on the sample tips and in the bucket. Measure the samples to estimate the alfalfa stand height. Repeat all of the previous steps two more times for a total of 30 stem samples (it is important to have a large sample size to have a more accurate representation of the field). Then reference the table below, comparing the number of larvae found per stem sampled and the overall height of the alfalfa stand to make a management decision.

Alfalfa weevil larvae can be identified by their wrinkled green body, black head capsule, and the presence of a white strip that runs lengthwise along their back (Figure 2). Third and four instar larvae will be approximately ¼ inch long, while the younger first and second instars will be smaller in size.

Figure 2. Alfalfa leaf with pinhole feeding damage, green alfalfa weevil larvae in different development stages (instars), and brown adults. Photo Credit – Julie Peterson, University of Nebraska

If action thresholds are met to warrant a spray treatment, the OSU and MSU “Field Crops Insect Pest Management Guide” is a great resource and can be found here: https://aginsects.osu.edu/extension-publications/msuosu-ipm-guide. Prior to spraying, always re-read the product label to reconfirm application rates, pre-harvest intervals, and other key pieces of information.

If the action threshold is met and there is sufficient growth to justify an early harvest, be sure to check the regrowth one week after cutting. This will ensure that the remaining alfalfa weevil does not persist into the second cutting to prevent strong regrowth.

More information about alfalfa weevils can be found on the alfalfa factsheet here: https://ohioline.osu.edu/factsheet/ENT-32. More information about sampling and the management thresholds from the University of Kentucky is here: https://entomology.ca.uky.edu/ef127.

Author: Glen Arnold

In recent years, dairy farmers and commercial manure applicators have been moving towards applying dairy manure to newly planted corn and soybeans.

Applying dairy manure to fields after crops are planted in the spring offers some advantages over applying manure before crops are planted. One advantage is corn or soybean planting not being delayed by the added moisture from the liquid manure. This delay can be costly if wet weather further delays spring planting. The second advantage is the liquid manure adding moisture to the soil that can enhance crop germination and emergence, especially if the weather turns off dry.

As soon as a field is planted, the manure can be applied. This is true for both corn and soybeans. The seed is protected by an inch or more of soil. In university research the application of 10,000 gallons per acre of dairy manure has not negatively impacted crop germination and emergence on corn or soybeans. If the crops are emerging, manure can still be applied to corn but not soybeans. Newly emerging soybeans can easily be killed by the application of liquid manure. Corn can tolerate the drag hose through the V3 stage of growth without an issue.

The nitrogen in the dairy manure will be a boost to the emerging crop. It is difficult to know how much of the ammonium nitrogen in the dairy manure will be available to the crop. The organic nitrogen portion will be a slow release over several years. The ammonium nitrogen in the dairy manure can be lost to volatilization and possibly leaching. In university trials of surface applied dairy manure, only about half the ammonium nitrogen applied seemed to be available for crop growth.

When a drag hose is utilized, the drag hose applicator commonly applies the manure at an angle across the field. The field needs to be firm enough to support the drag hose to avoid scouring the soil surface and burying small corn plants or further burying seeds. Fields that are spring tilled are not good candidates for a drag hose. No-till fields, stale seed beds, fields with dead or alive cover crops, and tilled fields that have been packed with heavy spring rain are usually good fields for a drag hose.

Additional on-farm manure side-dress plot results can be obtained by clicking on the On-farm Research link on the OSU Extension Agronomics Crops team website at http://agcrops.osu.edu/ or E-fields at https://digitalag.osu.edu/efields or follow OSU Extension’s manure research on Facebook at: Ohio State Extension Environmental and Manure Management.

Ohio State University Agronomics Crops Team Youtube channel is https://www.youtube.com/watch?v=S0nhw3GG6Q8&t=1s