Jul 7, 2016
Downy mildew on cucumber reported in Ontario

On July 5, downy mildew was identified on field cucumbers in Kent County, Ontario. Kent County is close to Michigan and it’s reasonable to assume that the disease will develop in our state soon. The sporangial counts in our traps have been low, but they have been detected over the last couple of weeks. The recent high temperatures have been wreaking havoc with the spore trap reels, causing the sticky coating used to “trap” the spores to melt. However, now that downy mildew is present in the Great Lakes region, growers should immediately move to a more intensive scouting plan and a general protectant spray program.

Google map showing location of Kent County, Ontario near Michigan.
Google map showing location of Kent County, Ontario near Michigan.

At this juncture, given the relatively dry conditions for many regions of the state, a less intensive spray program could be considered. This spray program could include mancozeb only or Bravo Weather Stik (chlorothalonil) only. Other downy mildew products could also be considered at this time and include the following as examples:

  1. Presidio (fluopicolide) + a protectant (Bravo Weather Stik or mancozeb)
  2. Zing! (zoxamide + chlorothalonil)
  3. Gavel (mancozeb + zoxamide)
  4. Zampro (ametoctradin + dimethomorph).

These particular fungicides may not be adequate when downy mildew pressure is high based on our data from the last two years, but could be helpful at this point when disease pressure is most likely to be low. Although Presidio has not fared well in recent Michigan State University Extension trials due to pathogen resistance, some growers on the east side of the state have reported efficacy, but Presidio should be mixed with a protectant fungicide (either Mancozeb or Bravo Weather Stik) if used. High downy mildew pressure is likely to develop later as the growing season continues. Once downy mildew is reported in the state and becomes more widespread, especially if the overall weather pattern becomes wetter with more frequent rainfall, the pathogen level will begin to build and additional fungicides should be used and include the following:

  1. Ranman (cyazofamid) + a protectant fungicide (either mancozeb or Bravo Weather Stik)
  2. The newer fungicide Orondis Opti A + Orondis Opti B

Hausbeck’s work is funded in part by MSU’s AgBioResearch.

Mary Hausbeck, Michigan State University

Source: Michigan State University Extension




Current Issue

Living Greens Farm enlarges product offerings, distribution

Balance the costs, benefits of grafting

Snap bean variety key for flowering in summer heat

Tests for viral diseases a guide to identify ToBRFV

Pursue best practices for fumigation, building soil microbes

New technology turns trusted irrigators into multi-purpose tool

Studies of biostimulant benefits address questions

Riverdance Farms finds success with farm-visiting crowd

‘Delighting’ the online customer ideal marketers’ goal

National Council of Agricultural Employer column: Wage increases naturally lead to job loss – ag included

Notes from the Farm column: Pipe layers spur ideas for installing irrigation lines

see all current issue »

75 Applewood Drive, Suite A
P.O. Box 128
Sparta, MI 49345

616.520.2137

Get one year of Vegetable Growers News in both print and digital editions for only $15.50.

Interested in reading the print edition of Vegetable Growers News?

Subscribe Today »


Be sure to check out our sister sites:
produceprocessingsm
website development by deyo designs