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Managing Cherry Disease Problems

M. Grabowski, UMN Extension

Photo 1:

Michelle Grabowski, UMN Extension Educator

Several disease problems have been observed on cherry trees this summer including powdery mildew and brown rot. When disease problems arise in the garden it is critical to identify what pathogen is causing the problem. There are different strategies to manage each disease and it is important to know what time of year management strategies should be applied. Many garden diseases can be significantly reduced if not eliminated with well timed cultural control strategies.

Find out more about identification and proper management of disease and insect problems of cherry, plum and apricot trees in the new UMN Extension publication Pest Management for the Home Stone Fruit Orchard.

Watch for Masked Hunters

Jeffrey Hahn, Extension Entomologist

Jeff Hahn, Univ of Minnesota Extension

Photo 1: Masked hunter adult - they can bite if you are not careful

Some people have been encountering a 3/4 inch long, dark colored, somewhat slender insect in their homes lately. This insect is a masked hunter, Reduvius personatus, a type of assassin bug (family Reduviidae). A masked hunter is a predator, feeding on a variety of insects. It can accidentally wander into homes during summer and is considered to be just a nuisance invader. No more than a few are usually seen at a time.

Fortunately, a masked hunter is not aggressive towards people, although it is capable of inflicting a painful bite if it feels threatened. It also is not a carrier of any disease. This is important as a masked hunter has been confused with kissing bugs which do transmit Chagas disease. Chagas disease is a potentially serious illness caused by a protozoan organism.

Kissing bugs also belong to the assassin bug family which helps explain the confusion between them. However, while kissing bugs belong to the subfamily Triatominae, masked hunters are in the Reduviinae subfamily. Kissing bugs are found in South America, as well as Central America and southern Mexico and are not native to the U.S. They get their name because of their habit of biting people on the face at night.

There is not any special control for masked hunters. Physical removal is the only necessary action that needs to be taken. If possible, capture and release any found outdoors. For more information, see Masked hunters,

Hollyhock Rust at its Worst

M. Grabowski, UMN Extension

Photo 1: Hollyhock rust on leaves

Michelle Grabowski, UMN Extension Educator

Frequent rains this spring and early summer have created favorable conditions for hollyhock rust. Hollyhock rust is caused by the fungal pathogen Puccinia malvacearum, which infects hollyhocks and related weeds like roundleaf mallow (Malva neglecta).

Early symptoms of hollyhock rust are easily missed. Small waxy yellow bumps form on the lower surface of the lower leaves of the plant. With age, these pustules turn reddish brown and a bright orange spot develops on the upper leaf surface. In wet years, spores from these early infections easily spread to infect leaves, stems, petioles and even flower bracts. Heavily infected leaves turn yellow and may wither and curl. This significantly reduces the plant's ability to do photosynthesis. The hollyhock rust fungi can survive from one season to the next in infected live crowns, as spores in infected plant debris, or on seed from infected plants.

M. Grabowski, UMN Extension

Photo 2: Hollyhock rust on stem and flower bracts

Unfortunately it is too late to prevent hollyhock rust this season. Keep plants as dry as possible by avoiding sprinkler irrigation and pulling weeds to improve air circulation around the plants. This will help to reduce spread of existing infections. Gardeners with infected plants should cut off the plant at ground level after flowering is complete. Infected plant material should be removed from the garden and buried, placed in a compost pile that heats up or taken to a municipal compost facility. Next year, mulch around the base of the plant to reduce the spread of spores from plant debris. Scout plants in early spring. Look for yellow waxy pustules on the lower leaf surface. Infected leaves should be removed and buried or composted.

Diseases in the Vegetable Garden

Michelle Grabowski, UMN Extension Educator

M. Grabowski, UMN Extension

Photo 1: Black rot is a bacterial disease of broccoli, cabbage, cauliflower and other brassicas.

This years frequent rains have created ideal conditions for many fungal and bacterial diseases in the vegetable garden. These pathogens need moisture to reproduce, spread and start new infections. Although gardeners can't change the weather, a few things can be done help plants dry out after rain or dew and to reduce the spread of disease.

1. Space plants to allow for air movement around the plants and through the foliage. Dense planting results in fruit and foliage that stay wet longer; a favorable condition for many pathogens.

2. Pull weeds. Weeds crowd the vegetable plant, steal nutrients and reduce air movement in the garden.

3. Completely mulch the soil with landscape fabric, plastic mulch, straw or wood chips. Many pathogens survive in plant debris and soil. Rain and irrigation splash water, soil and pathogens onto the lower

M. Grabowski, UMN Extension

Photo 2: Angular leaf spot on cucumber

leaves of the plant. Mulch provides a barrier that reduces splash dispersal of the pathogen from soil to plant. In addition, mulch keeps moisture in the soil and reduces humidity in the plant canopy.

4. Stake vining plants like tomatoes, cucumbers and runner beans. This will improve air movement around the plant and facilitate drying of the leaves and fruit.

5. Do not work in plants when leaves and fruit are wet. Fungal and bacterial pathogens reproduce under wet conditions and can easily be spread on a gardeners hands or tools at this time. Wait until plants have dried completely before working in the garden.

6. Pinch off heavily infected leaves and fruit and remove them from the garden. Many leaf spot and fruit rot diseases produce new fungal spores or bacteria in every leaf spot. These pathogens are easily

M. Grabowski, UMN Extension

Photo 3: Early blight on tomato

spread through the plant to new leaves and developing fruit. Infected plant material can be buried, placed in a compost that heats up or taken to a municipal compost facility.

Remember many plants tolerate some leaf infection and still produce a good crop. Use the steps above to reduce the spread of disease and minimize it's impact on your final harvest.

Karl Foord, Extension Educator - Horticulture

Karl Foord

Photo 1: Some of the plastic tunnels that provide optimum growing conditions on the Untiedt Vegetable Farm

Karl Foord

Photo 2: Sweet corn on Untiedt Farm

Karl Foord

Photo 3: Trellised tomatoes on the Untiedt Farm

Karl Foord

Photo 4: More trellised tomatoes on the Untiedt Farm

Karl Foord

Photo 5: Trellised cucumbers on the Untiedt Farm

Karl Foord

Photo 6: Trellised canteloupe on the Untiedt Farm

Karl Foord

Photo 7: Onions on Untiedt Farm

Karl Foord

Photo 8: Honeybee hives on the Untiedt Farm

Karl Foord

Photo 9: Protective tree barriers on Untiedt Farm

If you are not already a member of a CSA (Community Supported Agriculture), I highly recommend that you consider becoming one. To be a member one pays an up front fee and receives weekly a box of currently maturing vegetables for 17 weeks of the season. This prepayment helps the farmer to achieve better cash flow for the operation and the member/shareholder gets a greater understanding how their local food is produced here in Minnesota.

To better understand where my food comes from I attended my CSA Farmer's field day. It was an enlightening experience. Not only did I see where my food comes from but also listened to Jerry Untiedt discuss how he handles various issues such as pest control and water management. I was especially impressed with the system developed for water management. All the water that runs off Jerry's plastic tunnels (Photo 1) is channeled into a natural wet area that acts in a holding capacity. When Jerry needs the water back, he pumps it back from the wet area and waters his crops.

You can see from the photos that Jerry's soil is quite sandy. With the amount of rain we have had this spring a great deal of applied fertilizer would simply have been flushed through the system and end up in our waterways. Note the sweet corn field (Photo 2) and the green plastic under the crop. This has been placed there to avoid such a loss for the farmer and then pollution for those downstream. I was very proud to know that the food I am eating is produced in a system that has been developed to avoid such problems.

Most of the vegetable acreage is under plastic providing optimal conditions for growth. This being among others: 1) lack of rain water falling on the leaves and potentially creating disease problems, 2) protection from the stong winds that buffet and damage the plants, 3) an enclosed space permitting the use of beneficial insects to control pests - in an open field they are more likely to dispurse than protect your plants, and 4) keeping the plants within an optimum growing temperature - especially critical given Minnesota's unpredictable weather patterns.

To make optimal use of space, a number of the crops are trellised such as tomatoes (Photos 3 & 4) cucumbers (Photo 5), as well as canteloupe (Photo 6). Other crops that cannot be trellised also do extremely well in the tunnels (Photo 7).

Jerry has honeybees (photo 8) and bumble bees on site to provide pollination services.

Jerry has realized that the winds in Minnesota can play havoc with plastic houses. To provide protection he has surrounded the farm with fast growing trees that slow the wind down (Photo 9). In my opinion, Jerry has been extremely innovative and environmentally sensitive as he goes about producing superior produce.

Adopt a farmer and get a first hand experience of where your food comes from.

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