Southeast Michigan vegetables regional report – September 4, 2013

As the growing season winds down, pumpkin growers struggle to control diseases.

The cool weather (49 to 87 degrees Fahrenheit) has kept insect pests in check, but disease epidemic continues. Late blight continues to be present in the area in both potatoes and tomatoes. The Phytophthora infestans, or causal agent of late blight, genotype is US-23 and is sensitive to mefenoxam (Ridomil products). This means that Ridomil products can be used and are recommended in field with late blight infestations. Check Michigan State University Extension’s fungicide recommendation for potatoes and tomatoes.

The weather outlook has low chances of precipitation for the rest of the week, and a 20 to 34 percent chance of rain for the weekend (Sept. 7-8). Check the disease risk forecast at www.lateblight.org and www.usablight.org to time your sprays.

Vegetable crops report

Sweet corn harvest will soon be complete. No European corn borers have been caught in the Monroe County trap. One western bean cutworm was trapped. Corn earworm moth counts in the Monroe and Lenawee county traps were seven and nine, respectively, during Aug. 27-Sept. 3.

As harvest of fresh market and processing tomato continues, it is time to scout for fruitworm damage. Fruitworms and corn earworms are the same pest, but they have different names according to the crop they cause damage on. As sweet corn harvest winds down, the moths can move into pepper and tomato fields and cause some damage in the fruit.

Pumpkins are bearing 10- to 18-inch fruit. Symptoms of sunscald, bacterial wilt and Phytophthora rot have increased in the last two weeks in southeast Michigan. Virus symptoms have been observed in several pumpkin fields. Even though aphids are present in low numbers, they can move virus from plant to plant.

Pumpkin diseases
Top row: Sunscald (left) and fruit rot (right) in pumpkins.
Bottom row: Mosaic-like symptoms, characteristic of virus (left),
and Phytophthora foliar symptoms (right).
Photo credits: Lina Rodriguez-Salamanca, MSU Extension

Growers continue to battle with powdery mildew. At this point in the season, fungicides with systemic and translaminar movement combined with adequate coverage are critical as powdery mildew infects the underside of the leaves.

Protect your foliage from downy mildew and powdery mildew. Remember that some of the fungicides that protect for downy mildew can help manage Phytophthora rots (see table with recommendation below). However, keep in mind the products for downy mildew are different to the products for powdery mildew, and the fungicide program for powdery mildew is protecting the crop from foliar loss, fruit sunscald and shriveled Jack-o-lantern handles. Remember to alternate between FRAC codes (Fungicide Resistant Action Codes) and read fungicide labels.

Table 1. Pumpkin key diseases control. Information compiled from Mary Hausbeck bulletins.

Product

FRAC code*

Recommended for management of:

Commercial name

Active ingredient(s)

Downy mildew

Phytophthora

Powdery mildew

Ranman

cyazofamid

21

Yes

Yes

No

Revus 

mandipropamid

40

No

Yes

No

Tanos

famoxadone/cymoxanil

11, 27

Yes**

Yes

No

Gavel 

mancozeb/zoxamide

M3, 22

Yes, before***

Yes

No

Presidio 

fluopicolide

43

Yes

Yes

No

Zampro

ametoctradin/dimeth

45,40

No

Yes

No

Pristine 

boscalid & pyraclostrobin

7,11

No

No

Yes

Quintec

quinoxyfen

13

No

No

Yes

Torino 

cyflufenamid

U6

No

No

Yes

Topsin M 

thiophanate-methyl

1

No

No

Yes

Fontelis 

penthiopyrad

7

No

No

Yes

Flint 

trifloxystrobin

11

No

No

Yes

Pumpkin key diseases control:
Alternate products, mix each with either: Dithane (mancozeb) or Bravo (chlorothalonil)  *FRAC= Fungicide Resistance Action Committee, products with the same number(s) belong to the same chemistry group; AVOID consecutive application of the same FRAC code.
**Not to be used alone, always tank mixed with different protectant fungicide or another fungicide with different FRAC code.
***Before cucurbit Downy mildew has been confirmed in the area.

Read the label and follow all instructions closely. Remember that the pesticide label is the legal document on pesticide use. The use of a pesticide in a manner not consistent with the label can lead to the injury of crops, humans, animals and the environment, and can also lead to civil or criminal fines and/or condemnation of the crop. Pesticides are good management tools for the control of pests on crops, but only when they are used in a safe, effective and prudent manner according to the label.

Do you have a surplus of produce? Are you on the lookout for a specific commodity? Michigan MarketMaker can help you. Learn more about MarketMaker at the Michigan MarketMaker website.

It’s that time of the year where you can build the soil health at your farm. Use the Midwest Cover Crops Council’s Vegetable Cover Crops Decision Tool to plan cover crops to improve soil health and enhance weed control, among many other benefits they provide.

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