East Michigan vegetable regional report – June 3, 2015

We are transitioning from perennial to annual vegetables, and are starting to see insect pressure on many crops.


Macomb County really caught up on precipitation this week. Michigan’s Bay and Thumb area missed much of that rain. It will be a great week for growing drip-irrigated vegetables. Near normal mean temperatures and above-normal precipitation is forecasted in the next two to three weeks in southeast Michigan. Over all, statewide we are forecasted to stay pretty dry for the next month.

Here are the rainfall and growing degree day (GDD) base 50 degrees Fahrenheit accumulations to date from Michigan State University Enviro-weather stations.

Rainfall and GDD summary


GDD (50F, March 1)

Rainfall (inches, April 1)














Asparagus is being put to bed (also called “lay-by,” or “renovation” in strawberries). Mow or pick the plot clean and apply a combination of pre-emergent and post-emergent herbicides labeled for asparagus. The Michigan State University ExtensionWeed Control Guide for Vegetable Crops” (E0433) has a great list of materials for asparagus and their efficacy against particular problem weeds. Tank-mixing two modes of action is a good way to prevent resistant weeds on your farm. A common lay-by program includes Tricor or Karmex, and Roundup or 2,4-D. Roundup and 2,4-D will cause damage to asparagus in the fern stage, so be sure to follow label directions for special application procedures, and pick it or mow it down before application to minimize fern absorption.

Field rhubarb is being harvested. A grower asked how much can they harvest at once. Ohio State University recommends you never remove more than one-third to one-half of the stalks, and stop harvesting when new stalks get spindly (usually through June). An old MSU publication, “Rhubarb cultural guidelines for Michigan,” says plants that have been in the ground for more than two years can be completely harvested to the ground, and a strong stand can be harvested again in late August. Stalks harvested too late are pithy and tough. Overall, rhubarb is incredibly tolerant to abuse and grows with the vigor of a weed.

Tomatoes are getting tall in greenhouses and fruit is starting to blush. Transplanted field tomatoes are being protected by wind with spun-bond fabric. I have been receiving lots of questions about pruning indeterminate tomatoes. Determinate tomatoes do not send out as many suckers and do not need as vigorous pruning. This is a sensitive topic, and with indeterminate tomatoes it is very much a personal preference. There are three prunes that are encouraged for indeterminate tomatoes.

  1. The most important prune to make is to manage suckers that start growing from between the main stem and each fully-grown leaf. Remove suckers (simple pruning) every three to four days while they are tiny, or clip suckers to half or one-third their length (Missouri pruning) if suckers get away from you because it reduces the amount of injured tissue exposed after pruning. Missouri pruning can also be important in sunny locations to shade fruit. If you want a multi-stemmed tomato plant, you leave a few of these suckers on near the bottom of the plant to develop into secondary stems. If you leave all your suckers on, fruit will be smaller than they could be. This New Hampshire guide, “Pruning Tomato Plants,” has a nice diagram of a one-stem and two-stem plant further in development. Notice the second stem was a sucker, but all others have been removed.
  2. You should also be removing full leaves from beneath the first fruit cluster to maximize airflow through their dense foliage. This is especially important in a greenhouse setting. During my visit, we saw some plants with flowers beginning to form below actively blooming flowers. According to pruning recommendations from multiple sources, these should be removed too. “Be ruthless” is a common phrase recurring in literature.
  3. The final prune removes the growing tip from the top of the plant above the last fruit cluster when it has reached the maximum height that is convenient for you, or when it has already produced seven or eight fruit clusters. This ensures the final fruits will “finish” instead of being neglected by the plant for more vegetative growth.

Greenhouse cucumbers are being picked at some farm markets. Field pickling cucumbers are going in fast.

Hops downy mildew is showing up readily, and those unable to control it with fungicides have to cut bines back to the ground and start over. This disease, among other social factors, moved the hops industry to the arid west in the 1920s and 30s. With more fungicide options than ever, we can successfully grow hops in Michigan. However, one must be vigilant to avoid being a source for a regional downy mildew infestation of commercial or hobby hop yards.

Snap peas are just about to flower at farms that I’ve visited.

In cole crops, we have been getting reports of, and have seen, flea beetles. These insects are very selective of particular varieties of leafy greens, often preferring kale, radishes and some Asian greens. Proper crop rotation and soil work in the fall should prevent populations from building, and spun-bond fabric tunnels supported by wires can be used to exclude these beetles on small farms. If a chemical treatment is needed, pyrethroids like Mustang Max and Baythroid are old standbys that have good activity on all of the other cole crop insect pests too.

A CSA and farm market grower asked me about baby corn this week. They already have a line of pickled fruit and vegetables, and wondered is it really Zea mays or is it some other species of plant? Can we grow that too? You can, and it’s quite a flexible crop to work with because it takes up less space and can be harvested from any variety of corn. You could do whatever is cheapest or use a heavy-tillering sweet corn variety; harvest the tillers for baby corn and save the main ear for sweet corn. You can also save space by planting corn seed much closer together than usual. Sow each seed about 4 inches apart in the row, but keep a similar between-row spacing as you would for sweet corn for easy harvesting.

Baby corn ears are best harvested when they are “canning size,” about 2-4 inches long and a third of an inch to two-thirds of an inch in diameter. They often reach this size between one to three days after silking, but some cultivars and individual ears may reach this stage at different times. Large-eared field corn varieties may even reach this size before silking. So, you’ll have to watch your plants closely and harvest a few each day to get a feel for it. Fresh baby corn can be pickled or canned or blanched and frozen within about five days.

Other notes

I caught 20-30 aster leafhoppers in lettuce last week, and they are going in for processing today, June 3, for their infectivity of aster yellows disease.

It is extremely important to scout your farm and garden for any volunteer potatoes right now. Last year we had late blight outbreak on potatoes and tomatoes, and this disease can overwinter on tubers. It is a neighborly thing to destroy volunteer potatoes immediately and avoid harboring the source of a very destructive disease.

Colorado potato beetles are out and already on eggplants and potatoes in some organic fields. They are back and hope you didn’t miss them too badly.

If you would like to support your farming community by hosting a MSU Enviro-weather station at your farm, please read about what you can do at Support Enviro-weather.

Please contact me at .(JavaScript must be enabled to view this email address) or 989-758-2502 to pick up any suspected disease samples, or send the diseased plant parts to MSU Diagnostic Services.

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