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Showing posts from August, 2018

Managing crop residue to reduce disease

By September, many crops have accumulated some level of leaf spot, fruit rot or other disease problems. Even if these diseases are not severe enough to reduce yields this year, many plant pathogens are able to survive in crop residue from one season to the next, resulting in disease problems in following years. Several basic cultural control practices can be used to reduce the risk of disease spread to other crops in this growing season and the next.

First diagnose any unknown plant diseases in the field. A few plant pathogens, like white mold or Tobacco Mosaic Virus are able to survive exceptionally long periods of time in soil and crop residue. It is important to identify these problematic pathogens early, remove infected plants promptly, and follow sanitation procedures specific to that disease to reduce the ability of the pathogen to survive on site.

While harvest is ongoing, remove infected plants or plant parts to prevent spread to neighboring healthy plants. Many common leaf spo…

Bacterial leaf streak of corn

Bacterial leaf streak (BLS), a relatively new disease, has been found in sweet corn in several locations in Minnesota this year. 

What is BLS?
Bacterial leaf streak is caused by the bacteria Xanthomonas vasicola and has been found in sweet corn, popcorn, seed corn and field (dent) corn. This disease was first identified in Nebraska in 2016 and has since been found in 9 states in the Midwest including Minnesota.

How to identify BLS?  Bacterial leaf streak causes long thin leaf streaks that may be yellow, tan, orange, or brown. The edges of the leaf streak appears wavy.  When back lit, a yellow halo can be seen around the streaks. Streaks first form between leaf veins and extend parallel to the leaf veins. In severe cases, leaf streaks may grow together resulting in large dead brown areas on the leaf.

Many other leaf problems can be confused with BLS. The best way to confirm BLS is through submitting a sample to the UMN Plant Disease Clinic.


What we know about BLS?  As a relatively new d…

Corn Earworm Alert: Aug. 30, 2018

By Bill Hutchison, Professor and Extension Entomologist

CEW adult, moth flights continue to be high near Blue Earth, and increased substantially this past week at Owatonna (now >70/night) and Rosemount (>175/night). As other crops continue to mature (e.g., tomato, peppers, green beans), late-planted or late-maturing sweet corn with fresh silks, will continue to be the #1 preferred host for CEW egg-lay. 

Recent flights have been supported by several recent weather systems, moving warm air from southern states, our way. Although we have observed various levels of CEW resistance to pyrethroid insecticides (bifenthrin, lambda-cyhalothrin) in recent years, our results so far this year have indicated good efficacy. 

If you are not finding good/excellent control, consider one of the diamide options (e.g., Coragen). See the VegEdge CEW page for moth flight updates at all locations:  https://z.umn.edu/3oyp
CEW egg-lay can continue throughout the next 4 weeks, as long as we maintain warm night…

New Podcast Episodes: Japanese Beetle, Pollinators, Diseases, and More!

If you have not yet checked out our new podcast on fruit and vegetable pest management, called "What's Killing My Kale," this is a great time to give it a listen. It's easy - just click on the episode titles, and hear the recording out of your phone or computer.

Despite the name, it's not just about kale. We release timely episodes on all kinds of pest topics, based on the insects, diseases, or weeds that are currently causing problems for Minnesota fruit and vegetable crops. The podcast is hosted by Annie Klodd and Natalie Hoidal.

Each episode is an interview with an expert - either a researcher, farmer, or Extension educator - about the latest and most effective ways to manage that pest.

Each episode can be found on the UMN FruitEdge website: https://www.fruitedge.umn.edu/kalepodcast

This month's episodes included:
Episode 12: How Much Do We Really Know About Japanese Beetles? (8/22/2018)
Episode 11: Pollinators and IPM part 3: Pesticides and pollinators with Kar…

Check Apple Ripeness with the Starch Iodine Test

We’ll soon be in the thick of apple harvest time! What’s the best way to tell if an apple is ripe?

There are several ways – 1) change in peel background color from green to yellow, 2) change in peel “overcolor” from green to yellow or red, 3) change in firmness from rock hard to being able to bite without breaking your teeth, 4) change to preferred flavor, which varies from person-to-person, or 5) change in flesh starchiness to sweetness as the starch is converted to sugar.

Not all of these methods work for all varieties. Peel background color can be hard to see, overcolor can change when background color is still green, and some apple varieties stay firm or crisp (like Honeycrisp).
The Starch Iodine Test As fruit ripen, they lose starch. Change from starchy to sweet is generally a good indicator of ripeness, and is used by many apple growers, along with the other methods mentioned above, to determine when to harvest their fruit.

The starch iodine test is a way to measure the percenta…

Five cover crops to try this fall after vegetables

The time has come to shop for fall-planted cover crops to sow after vegetable harvest. Fall cover crops benefit vegetable production in numerous ways, including soil building, erosion control, weed suppression, and nitrogen fixation.

Certain species will overwinter into the spring, while other non-winter hardy species are meant to be terminated naturally with the first killing frost of the fall. Each species has unique traits and benefits, and species can be planted in mixes or “cocktails” to combine the benefits of each. Here are 5 popular cover crops to try this fall for vegetables:
Winter rye (cereal rye) Winter rye is one of the most cold-hardy cover crops for Minnesota, which contributes to its popularity as a winter cover crop. This high biomass species not only contributes large amounts of organic matter and provides erosion control, but is also a top pick for weed suppression due to its tall canopy and rapid establishment.


How winter rye manages weeds: First, the disturbance c…

Basal rot of onion and garlic

Basal rot is a common disease of onion and garlic in Minnesota. Growers should monitor garlic and onion crops for symptoms of basal rot when the crop is in the field and at harvest.

Caused by the fungus Fusarium oxysporum f. sp. cepae, basal rot can occur in all Alliums but causes most significant damage on garlic and onion. Bulb rot begins in the field and can spread post-harvest.
What to look for when scouting in the fieldStunted plants with yellow foliage and poor bulb development Plants with tip burn, yellow and collapsed foliage Plants pull up easily from the soil, few to no roots remain attached Firm brown rot begins at the basal plate and moves up the bulb White fluffy fungal growth may be present in humid conditions How to inspect the harvest Press on the base of the bulb where the roots attach. Infected bulbs will feel soft and give slightly under pressure. Infection can be confirmed by pulling back the wrapper layers and looking for rot in the bulb or cutting the bulb in h…

Late blight found on MN tomatoes

Late blight has been identified on tomatoes in Otter Tail County, MN. Growers in that region should take immediate action and scout tomato plantings for symptoms of late blight.

Late blight is caused by the pathogen Phytophthora infestans which can only survive Minnesota's winters if sheltered in a cull pile or a warm compost pile. As a result late blight often needs to be brought into the state on infected transplants, tubers, or on windblown sporangia. Once the pathogen arrives, it needs cool wet weather to thrive and spread.


How to identify late blightExamine lower leaves and leaves in the center of the canopy where humidity is highEarly infections have greasy gray leaf spots and powdery white mold may be visible on the lower leaf surface if humidity is highSpots grow into large, dark brown blotches with a green gray edgeLeaf infections spread quickly through the leaflet and into the petiole, resulting in clusters of brown foliage Stem infections are firm and dark brown with a r…

Weighing the Risks: Corn Borer and Corn Earworm in Sweet Corn

Authors: Anthony Hanson, Eric Burkness, & Bill Hutchison
Have you seen corn borer or corn earworm this year? UMN Researchers give recommendations, and explain how they use flight data on European Corn Borer and Corn Earworm to help predict the risk of infestation.


European corn borer (ECB), Ostrinia nubilalis, can cause damage to sweet corn by tunneling through the stalk, ear loss by shank feeding, and tunneling through the ear along with direct feeding on ear kernels (Fig. 1). 
In most years, the primary concern is feeding damage within the ear, reducing marketability to both fresh-market and processing sweet corn. The multi-generation strain of ECB typically has two generations in Minnesota. Given the number of above-average temperatures this summer, we are at ~225 ECB degree-days (>50F) ahead of 2017, for many locations; as of July 31, >1500  degree-days have accumulated for southern, central and NW MN (Fig. 2).  Risk of European Corn Borer It’s now time to review moth fli…

What’s Happening on the Farm Information Line?

Author: Robin Trott, Horticulture Extension Educator - Douglas County
Three of the most frequently asked questions on the FIL right now are about tomato leaf curl, pesticide drift, and weed identification. Robin reveals the answers in this article. First, what is the Farm Information Line? The Farm Information Line is a service provided by University of Minnesota extension to help farmers across the state find solutions to all their Ag questions. 
I have manned the line for three years, and find that many of the calls and emails I receive are from small, specialty crop producers who are having issues that impact their bottom line.
This monthly column will review the most common questions I receive, and provide some solutions to those questions.  If you have a topic you would like me to include in this column, please email me at trot0053@umn.edu, and I’ll try to get you an answer. Popular Questions from JulyDuring the month of July I had 3 top questions regarding fruit and vegetable producti…