Southeast Michigan vegetable regional report – August 24, 2016

Heat and drought subside as harvest continues.

Orange pumpkins are fully mature and will not grow any larger. Keep these pumpkins shaded, or harvest and store them. Photo: Marissa Schuh, MSU Extension.

Orange pumpkins are fully mature and will not grow any larger. Keep these pumpkins shaded, or harvest and store them. Photo: Marissa Schuh, MSU Extension.

Weather

Rains the last week have been helpful for many crops and have lessened the need for irrigation. Harvest has slowed down, but is still being carried out in most fields. Temperatures have been a bit lower.

The table below presents rainfall (in inches) for the Michigan State University Enviro-weather stations in southeast Michigan. Degree-day is base 50 degrees Fahrenheit since March 1 for 2016 and the range of degree-days at the same station in the last five years.

Rainfall and degree-day totals as of Aug. 24, 2016

Weather station

Rainfall (in) last week

Rainfall (in) since April 1

Degree-days

5-year range

Commerce

0.39

12.84

2,300

1,856-2,337

Blissfield

1.71

12.21

2,413

N/A

Hudson

0.12

9.19

2,266

1,955-2,556

Petersburg

0.14

9.48

2,263

1,943-1,504

Crops

Sweet corn growers should be aware that corn earworm is on the move to the south of us, with trap catches in northern Indiana often reaching 100-200 corn earworm moths per night. Trap catches in other areas of Michigan have also risen recently, with some parts of Michigan catching 50-80 moths per night. The threshold for this pest is 10 moths per night, so there are a lot of moths out there. If you have traps on your farm, check them daily now as moth populations could be high in southeast Michigan as well. Numbers as high as those in Indiana suggest that moths are being carried from the South on northerly winds, and if sweet corn is in the vulnerable silking stage, treatment every two to three days is judicious.

Growers of tomatoes, especially fresh market tomatoes, and peppers may want to also keep an eye out for fruit damaged by corn earworm. In tomatoes, the larvae will bore into green tomatoes from the stem-end inward. They seldom enter ripe fruit, and if they are present in a tomato you will see a cavity that is deep, watery and littered with frass. In peppers, this pest is more likely to show up when corn is past the silking stage and thus less appealing to egglaying moths. The larvae will burrow into peppers, which will often lead to secondary infections that cause decay.

Another pest that may impact these crops and others, the brown marmorated stink bug, has not been caught in local traps, according to MSU Extension’s brown marmorated stink bug report for Aug. 19, 2016. For information about identifying this pest, see “How to identify a brown marmorated stink bug,” by MSU Extension.

Generally, cole crops look healthy. Cabbage is being harvested. Cabbage plants planted for later harvest are at various stages, from cupping for early head formation. Various caterpillar pests are present, though the thresholds for damage depends on life stage and what product the cabbage is being grown for.

Acorn squash is ready and being harvested. Some spaghetti squash is also ready. Again, growers of all cucurbit crops should keep an eye out for downy mildew, and preventative measures for powdery mildew should also be taken. Downy mildew has been confirmed in Hillsdale County cucumbers, so the spores are out in southeast Michigan and recent rains will aid its spread. Preventative fungicides should be applied.

Banana peppers and bell peppers are being harvested. Blossom end rot has caused considerable damage to banana peppers this season. This disorder is related to calcium uptake, though its presence in a pepper field doesn’t mean calcium amendments are necessary for the success of future pepper plantings. Blossom end rot is also heavily influenced by weather, especially by drought cycles. This year’s hot temperatures and sporadic rainfall are likely accountable for a majority of this year’s blossom end rot. If calcium is a concern, soil testing is a valuable tool in assessing which amendments could be beneficial.

Potato harvest has begun and the tubers coming out look good. The Michigan Late Blight Risk Forecasting model suggested that the lack of humidity and cooler temperatures reduced the risk of the disease early in the week, but the risk of infection has increased as temperatures have risen. Risk is high in Monroe County for the next five days.

Processing tomato harvest continues.

Pumpkins in some parts of southeast Michigan are looking ready to harvest, which is quite early. If your pumpkins are orange and leaves are starting to die back due to age, they will get sunburn and begin to rot if left in the field. Protect them by harvesting them and keeping them in a barn until cooler weather arrives and people are in the mood for autumn-themed/Halloween products.

If you have any plants that you believe may have a disease, please contact me at .(JavaScript must be enabled to view this email address) or 517-264-5309 to schedule a pickup, or send the affected plant parts to MSU Diagnostic Services.

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