Sightings from the Field: Week of August 9-13

Authors: Annie Klodd and Natalie Hoidal, UMN Extension Educators for fruit and vegetable production

This was a week of the good, the bad, and the ugly. Here are some of the things that occurred this week throughout Minnesota:

Clear differences among pumpkin varieties in trial

The field tour of the pumpkin variety trial by Annie Klodd and Rod Elmstrand (Rod's Berry Farm) took place on in the evening of Monday, Sept. 9. Thank you to the 40 growers who attended despite the rain! We compared fruit from 32 different varieties from the trial, stepped into the field between rain showers to discuss pumpkin management, viewed a pest management calendar made by Natalie Hoidal, and enjoyed dinner and dessert prepared by Rod and Sara Elmstrand. Thank you to MFVGA for sponsoring the event.

Annie and Rod describe traits of 32 pumpkin varieties. Photo: Allison Sandve, UMN Extension.

While we have not harvested or collected data yet, some stand out varieties at the field tour included: Hermes, Zeus, Orange Sunrise, Kratos, and several experimental varieties including RPX 6208 (Rupp) and SPU 3269 (Sakata). Warty Goblin, Specter, and RPX 6229 (a new tan variety) caught our eyes as well.
 

Warted pumpkin varieties on display at a UMN/MFVGA field day on Sept. 9, 2019. Photo: Allison Sandve, UMN Extension.

High tunnel peaches

Dan Sheild in Shafer, MN is successfully producing organic peaches and apricots in a high tunnel. This week, Dan sent us photos and a sample of the recently harvested peaches. The variety that ripened last week is Blushingstar. He also grows Contender, which ripened earlier this summer. His apricot varieties include Afghanistan and Robada.

Peaches grown in a high tunnel in Shafer, MN, shortly after harvest. Photo: Dan Sheild.

2,4-D and dicamba damage confirmed on grapes

At least two vineyards in Minnesota have confirmed high levels of 2,4-D and dicamba damage throughout their vineyards, from herbicide drift from nearby crop fields. The damage was first observed in mid-July but was confirmed through test results this week. The cut-off date for application of dicamba to dicamba-tolerate crops is June 20 in Minnesota. 2,4-D and dicamba are very damaging to grapes and other fruit and vegetable crops, and in some cases can cause substantial revenue losses for several years after the damage occurs. Further details on these events may be released in a future newsletter.

Characteristic 2,4-D damage on grapevines. Photo: Mike White, formerly Iowa State University.

Phytophthora infestations on pumpkins

Pumpkins infected by phytophtora. Aug. 10, 2019. Photo: Natalie Hoidal.

Phytophthora blight is a potentially devastating disease of cucurbits and peppers. This week we saw a field of pumpkins totally wiped out by this disease. If you're seeing diseases in your fields, it's always a good idea to get a diagnosis from the Plant Disease Clinic so that you can take appropriate precautions. A few tips for preventing phytophthora include:

• Maintain a full four year rotation, only planting cucurbits or nightshades every fourth year in areas that have been infected. 
• Try raised bed systems in low lying areas if you've got the right machinery for making beds - this will help to improve drainage. Phytophthora spores move through water, so fields with poor drainage are more likely to have problems. 
• Wash all equipment with a 10% bleach solution or another disinfectant after you've been in an infected field. 
• Power wash boots and harvest equipment on a regular basis. 
• Be mindful and cautious about moving from infected fields into clean fields. Always try to start the day in the cleanest fields, and progressively move towards more infected fields. 

For fungicide recommendations and more information, see the Midwest Vegetable Management Guide (page 117 for Phytophthora info).