East Michigan vegetable update – June 14, 2017

Bloom has begun for early melons, growth has been slow-to-steady for warm season crops without irrigation.


We’ve gone from moisture excess to deficits across much of our region, with moisture at depth. Deep rooting plants will reach for it, but shallow rooting crops and young establishing crops could use a drink.

Here are degree day (base 50 F since March 1), rainfall (inches since April 1) accumulations, and soil temperature ranges (Fahrenheit over the last week) to date from Michigan State University Enviro-weather stations in the region.

Rainfall and growing degree-day totals as of June 14, 2017


GGD (+ added from last week)

GDD five-year average

Rainfall (+ added from last week)

Rainfall five-year average


596 (+ 157)


6.89 (+ 0.00)



644 (+ 164)


5.38 (+ 0.00)



724 (+ 171)


9.07 (+ 0.11)



679 (+ 170)


8.06 (+ 0.00)



655 (+ 164)


6.92 (+ 0.00)



673 (+ 161)


5.20 (+ 0.01)



580 (+ 155)


9.99 (+ 0.03)



658 (+ 164)


7.45 (+ 0.00)



655 (+ 165)


6.66 (+ 0.00)



567 (+ 155)


6.61 (+ 0.00)



Sweet potatoes are beginning to root but they could really use some water or humidity to offset what they’ve respired.

Cole crops are hosting the pupal cases of imported cabbage worm, which means an entire generation of caterpillars ate their fill on crop plants and are now turning into white butterflies. I still have not seen diamondback moth but growers have and started treatments.

Sweet corn at V6-V7 in central counties. Earliest plantings in SW counties are silking. Soil temps have maxed out over 70 F for nearly five consecutive days. That is a good sign that seed corn maggot egg-laying has stopped. However, with our dry conditions, planting is not recommended without irrigation to activate pre-emergent herbicides.

Some transplanted watermelons and cantaloupes on plastic are now blooming. Insecticides should only be applied to these blooming crops after dinner time to protect your pollinators. No fruit without them.

It is getting late to start transplants or seed these crops because they are warm season crops that will be reaching maturity as days are getting shorter and nights are getting cooler. Ripening in those conditions takes longer, and sometimes doesn’t happen at all.

Pickling cucumber plantings continue in the Saginaw Valley. Growers are concerned with acreage cuts this year. Some seedling die-offs have occurred in very low percentages, but no seedcorn maggots or obvious damping-off symptoms were found. Parthenocarpic (seedless) varieties have started going in. Bees are being organized for field placement.

Seeded squashes and pumpkins are still being planted and wrapping up in southern counties. Once again, seedcorn maggot threats have reduced with increased soil temps, but irrigation should be considered after seeding to activate herbicides.

Potatoes are putting out flower buds, and have been hilled a second time. Growers should take action to limit volunteers from becoming a disease vector for new potato and tomato plantings this year. That means killing them off in fields and cull piles.

MSU Department of Entomology professor Zsofia Szendrei’s lab found seven species of bumble bees visiting potato flowers last summer, though potatoes do not require pollination for producing a crop. They found no detectable differences in foraging behavior between neonicotinoid treated crops, and untreated crops. However, the team did collect 58 species using traps in potato fields, including honey bees, with the majority of bees found at field edges.

So, foliar contact insecticides on potatoes during bloom and during the day time could potentially affect the managed pollinators, in addition to the wild pollinator community at large. This can create a tricky situation when mixed with other flower crops that do depend on pollinators. Evening and night sprays appear to be the best solution at this time.

Tomatoes are at all stages and looking great where I’ve seen them. Some growers have reported botrytis gray mold in greenhouse situations. Field planted varieties have been treated to excellent growing conditions on irrigated ground this last week. They've jumped noticeably.

Pepper plantings are nearing completion. Early plantings having a rough go in early bareground plantings. Soil temps were better for them in plastic beds. But, the air temps still held them back and some plantings are blooming at mid-shin height. With this heat, they should be aborting flowers, which would be good so the plant puts more energy into growing plants. Later plantings should fair better if watered.

Red beets are starting to bulk up. Turnips are getting pounded by flea beetles. In and among other cole crops, I would hazard a guess that these beetles prefer turnip, and they might serve as a decent and cheap trap crop.

Early strawberry varieties are small and misshapen this year due to a variety of comingling environmental conditions, but primarily from extreme wind and lack of good pollination conditions when those varieties were in bloom. Later varieties, while still impacted by winter and spring cold snaps, saw better pollinating conditions.

Onions are going to be under pressure from onion thrips with this hot dry weather. Scouting should drive sprays for this pest. In some years, just two sprays of Movento when thrips populations reach 1 thrips per leaf, can limit the population growth significantly, and be as effective as eight weekly sprays of other products.

Incorporating heavy rye residue can be tricky. One grower in the region turned to burning it off. I would suggest checking for any required township permits for burns of that scale.

Please contact me at phill406@msu.edu or 616-901-7513 to grab any suspected disease samples from your farm, or send the diseased plant parts to MSU Diagnostic Services.

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