MSU Extension Vegetables

Weather

A new weather system will be moving in week’s end, bringing with it scattered rain and warmer temperatures. The cooler temperatures we’ve had in the last five days are well suited to field work and transplanting.

The table below presents rainfall (in inches) for the Michigan State University Enviroweather stations in southeast Michigan, as well as growing degree-days (GDD) calculated using the Baskerville-Emin Method. Degree-day average for Commerce and Hudson is over five years, while Deerfield is over two years. Soil temperature range in Fahrenheit at 2-inch soil depth, and rainfall is in inches, with parenthesis indicating change since last Wednesday. For a refresher on degree-days and how to get this information in your area, see “Accessing growing degree days with Enviro-weather” from MSU Extension.

General notes

The remnants of tropical storm Alberto rolled through May 30 and brought a flush of black cutworm moths with it. Eggs are likely hatching now, so keep an eye out for leaf feeding in fields where the plants are still relatively small. Black cutworms have a wide host range and are known to feed on sweet corn, tomatoes, vine crops and cole crops. Caterpillars won’t be large enough to cut plants until June 14 or 15, but at this smaller, leaf-feeding stage, digging around at the base of impacted plants can reveal the cutworm, which will be dark with a greasy appearance. For more information on this pest, see MSU Extension’s “Black cutworms snip sweet corn seedlings early in the season.”

As field corn reaches heights of 6-12 inches tall, growers will start making herbicide applications, meaning specialty crop growers should keep an eye out for pesticide drift. With the limited planting windows, field corn is all over the place development-wise, so we will likely have more windows for potential drift this season. If you suspect drift, file a complaint with the Michigan Department of Agriculture and Rural Development by filling out an online form or calling MDARD at 1-800-292-3939 (be clear you have a pesticide drift complaint to get routed properly).

Crops

Asparagus picking is winding down. After final harvest is a good window for weed control. As final pickings approach, there are a couple of options. A thorough clean pick can be followed by an application of glyphosate, dicamba or 2,4D. Another option is Spur, which can burn spears (making it a good post-last pick product), but provides good control of composite weeds like Canada thistle. For a full listing of products and some tips for use, “2022 Weed Control Guide for Vegetable Crops.”

In cole crops, diamondback moth is the main caterpillar pest being seen in our area. These caterpillars are small (even at their largest, they’re under a half inch long), with bodies that taper at both ends. These larvae make more numerous, small holes in the plant and have higher treatment thresholds than cabbage looper and imported cabbage worm. See last week’s report for thresholds, which are dependent on crop and crop age. In many fields, this pest is still below threshold, but adults are flying and the weather is predicted to warm, both of which will mean an increase in pest numbers and activity.

On smaller, organic farms, some imported cabbage worm is being seen in addition to diamondback moth. Flea beetles are also an issue. They have been getting under row covers on some farms. These insects are very mobile, so using chemical controls can be difficult. There are organic products that work, but they don’t have a long lasting residual, and when this is combined with the biology (a highly mobile insect with continual emergence from the soil near and in the planting), it can appear the products have no effect. Some growers have good luck with Entrust, which tends to stick around a little longer than some of the other materials.

The earliest green bean plantings are starting to flower.

Melons are going out.

Peas are flowering, some of the earliest plantings have inch-long pods.

Pepper planting continues.

Potatoes are being hilled. Adult Colorado potato beetles are feeding.

In spinach and chard, leafminer has been an issue this year, mainly on organic farms. When this insect is present at lower levels, picking and disposing of leaves with minor damage can help reduce insect numbers for next year, as well as managing weeds like lambsquarters, nightshade, and chickweed, which can also host this insect. If populations are high, Entrust has shown to be the most effective organic product available in trials. For a full summary of products available, see the “Organic Production and IPM Guide for Spinach” from Cornell.

Spinach leafminer produces irregularly-shaped, rounded mines in leaves as the larvae feed. Photo by Whitney Cranshaw, Colorado State University, Bugwood.org.

Tomato planting is wrapping up soon on some farms, staked tomatoes are on their first tie. I saw an incidence of tomato mosaic virus this week; if you have plants that were grown in a greenhouse that also does ornamentals, keep an eye out for bumpy fruit and pale, irregular rings on leaves. I have testing strips for plant viruses that I can use for quick, in-field diagnosis. Feel free to call me at 517-264-5309 if you have any suspect plants.

A note for farms growing produce typically consumed raw. If you are a farm that has to comply with Food Safety Modernization Act (FSMA), you may be entering the “as close as practicable to harvest” window for testing your irrigation/spray water. FSMA gives you a window to build a water-quality profile, so testing this year isn’t mandatory, but can help you work out the kinks in your testing regime and is a good agricultural practice.

For information on what to look for in a water testing lab, see MSU Extension’s “Find the right water testing lab for Food Safety Modernization Act Produce Safety Rule compliance,” and for an interactive map of Michigan labs that offer one of the FSMA-allowed testing methods, see the “FSMA Water Testing Lab Map.”

Contact me any time at 517-264-5309 or schuhmar@msu.edu with pest identification requests and questions. I tweet about what I’m seeing @SoutheastMIVeg.

Meetings

Registration for the 2018 Weed Tour on June 27 is now open. This on-campus event highlight weed identification and control strategies.

Learn more about vegetable research and management June 28 during the Agriculture Innovation Day: Focus on Fruit and Vegetable Technologies. This year’s event is being hosted at the Southwest Michigan Research and Extension Center in Benton Harbor, Michigan. More event details and registration can be found at Agriculture Innovation Day: Focus on Fruit and Vegetable Technologies.

It is never too early to make accommodations to attend Great Lakes Fruit and Vegetable EXPO, Dec. 4-6 in Grand Rapids, Michigan. Hotel blocks are open and tend to go fast. The combination of grower-focused, research-backed presentations and an exhibit hall featuring a diverse set of vendors make it a can’t-miss event.