If you notice mild symptoms of an infection, trim off the affected leaves. Then, sit back and let your crop grow, continuing to monitor for signs of disease. With any luck, your beet roots will grow large enough that you can still eat them.
First, you can plant trap crops, like nasturtiums, nettles, and asters to attract aphids. In between your trap plant and your beets, grow repellent plants like marigolds, dill, and catnip.
If you want to skip the chemicals, your best bet is to pull the plants and destroy them if they contract Southern blight. Then, turn the soil at least four inches deep to expose the fungus to sunlight.
Southern blight has a wide host range, affecting vegetable and fruit hosts such as tomato, pepper, onion, beet, strawberry, lettuce, cucumber, melon, carrot and asparagus. It also will attack ornamental plants such as aster, dahlia, impatiens, black-eyed Susan, peony, daylily, rose, salvia, petunia and hosta.
The southern blight fungus is saprophytic and can grow on a variety of substrates found in soil. Freezing temperatures will kill the mycelia, but the sclerotia will persist at temperatures down to 14 F. High temperatures (>85 F), moist conditions and an acidic soil favor disease development. The germination of sclerotia occurs at pH levels of 2-5 and is actually inhibited at pH levels above seven. Sclerotia are spread by the movement of infested soil and plant material, in contaminated irrigation water, and through use of contaminated tools.
Southern blight can be difficult to manage when high levels of inoculum are in a field. Growers should not plant susceptible crops in fields that have a history of southern blight for at least 2-3 years. Rotate vegetables with corn, wheat, sorghum or small-grains. If growers bury infected plant debris and sclerotia with deep plowing it is possible to greatly reduce inoculum levels for next year. Be sure the previous crop has decomposed completely prior to planting. Maintain adequate soil pH for optimum plant growth. Lower soil pH will encourage disease development.
Fungicides containing PCNB and azoxystrobin are labeled for southern blight control on many but not all vegetables and will have varying levels of effectiveness. Work at Clemson University showed that Priaxor fungicide when directed at the base of tomato plants gave the best control of southern blight. All fungicides are more effective if applied as preventive treatments rather than after the disease is found. Do not use one active ingredient for all treatments, alternate the use of two or more different active ingredients to minimize fungicide resistance problems.
Cercospora leaf spot, caused by the fungus Cercospora beticola, occurs wherever table beets, swiss chard, sugar beet, and spinach are grown and is one of the most important diseases affecting the Chenopodium group. It can result in significant losses, particularly in late summer when conditions are favorable (high temperatures, high humidity, long leaf wetness periods at night). Leafy greens become unmarketable, and beet roots fail to grow to full size when disease is severe.
There are actually many products, both conventional and organic, that are effective in controlling Cercospora leaf spot and other foliar diseases of beets. For optimum results use protectant fungicides preventively, before disease symptoms become severe.
Unfortunately, many new vegetable gardeners can be turned off to gardening by crop loss from very common and preventable fungal diseases. One minute the plants can be thriving, the next minute leaves are yellow and wilting, covered in spots, and the fruits and vegetables they were so excited to grow themselves look rotted and distorted. These gardeners wonder what they did wrong when, in fact, sometimes fungus just happens regardless of your level of gardening expertise. One such fungal disease that gardeners have very little control over and is barely noticeable until it is too late is southern blight on beets. What is southern blight? Continue reading for the answer.
Southern blight is a fungal disease that is scientifically known as Sclerotium rolfsii. In addition to beet plants, it can affect over five hundred plant varieties. Some fruits and vegetables it can commonly affect are:
Southern blight is a soil-borne disease that is most prevalent in semi-tropical to tropical areas and the southeastern U.S. However, it can happen in any location where cool, wet spring weather quickly becomes hot, humid summer weather. Southern blight spores spread the most on humid days that are about 80 to 95 degrees F. (27-35 C.), but they can still spread on cooler days. It is spread from direct plant contact with infected soil or the splashing up of infected soil during rain or watering.
In plants that form fruits on aerial stems, like tomatoes, symptoms of southern blight will first become present on lower stems and foliage. These plants can be diagnosed and treated before resulting in fruit loss. However, tuberous vegetables and vegetables that form in the soil, like beets, may not be diagnosed until the vegetables are severely infected.
Beets with southern blight are usually not diagnosed until the foliage begins to yellow and wilt. By that time, the fruit is full of rotted lesions and may be stunted or distorted. An early symptom of southern blight on beets that is often overlooked is the thin, white, thread-like fungus spreading through and on the soil around beet plants and on the beet itself. This thread-like fungus is actually the first stage of the disease and the only point at which the vegetable may be possibly treated and saved.
There is no guaranteed southern blight treatment once the disease has infected the vegetables. At early signs of this disease, you can use fungicides on the plants and the soil around them, but if the vegetables are already distorted and rotting, it is too late.
Prevention is usually the best course of action. Before planting beets in the garden, treat the soil with fungicides. This is especially important if you live in a location prone to southern blight or have had southern blight previously.
Young plants can also be treated with fungicides as soon as they are planted. You may want to try new, disease-resistant varieties of beet plants whenever possible. Also, always sanitize your garden tools between uses. Soil-borne southern blight can be spread from one plant to another from a dirty garden trowel or shovel.
This report corresponds with the predicted high late blight risk in southern areas of the state (Photo 3). We strongly recommend intensive monitoring of potato crops for late blight detection. Samples should be submitted to MSU Diagnostic Services and reported to MSU Potato Disease or your local MSU Extension expert (find an expert or call 888-678-3464).
Late blight is caused by P. infestans, which favors 60-80 degree Fahrenheit temperatures, high humidity and frequent rainfall. Our online forecasting tool calculates disease severity values (DSVs) based on the duration of temperature and relative humidity conditions that are favorable for disease development. Accumulated DSVs (based on early May emergence) are used to determine the local late blight risk level, indicated by the color of the map marker pins:
One of the ways Roosevelt Row has addressed Phoenix's planning woes is through its Adaptive Re-Use of Temporary Space (A.R.T.S) Program, launched to address urban blight in the downtown area. This project puts vacant lots to productive use through crafts markets, public art, cultural festivals, outdoor films, and concerts. One of the A.R.T.S. most successful projects, the Roosevelt Row Growhouse, has turned a once-blighted lot into a lush and productive space, relatively uncharacteristic of the harsh desert environment.
"Why not utilize the land for something productive and beautiful?" asks Kenny Barrett, one of the Growhouse's founders. With 75 percent of the growing vegetable beds located in typically blighted right-of-way spaces, residents are often inspired by the innovative and productive ways such spaces can be used.
Bacterial leaf spot caused by Pseudomonas syringae pv. aptata in red beet crops. A) Severe, coalesced lesions on a leaf. B) Bacterial leaf spot symptoms on leaves and seed stalks (black arrow) in a table beet seed crop. C) Bacterial leaf spot symptoms on beet seedlings. D) Dark black, water-soaked lesions on a beet leaf following a rainstorm.
What is Southern blight? Southern blight is a lethal fungal disease that is most common in the tropics and subtropics. This disease causes damage in the southern U.S. and can even cause problems in temperate locations like Wisconsin during periods of warm, moist weather. Southern blight has a wide host range, affecting over 500 plant species. Vegetable and fruit hosts include tomato, pepper, onion, beet, rhubarb, strawberry, lettuce, cucumber, melon, carrot, asparagus and parsley. Ornamental hosts include aster, black-eyed Susan, dahlia, daylily, gladiolus, hosta, impatiens, peony, petunia, rose, salvia, sedum and viola. Small woody trees and shrubs can be affected as well.
What does Southern blight look like? Southern blight initially leads to a water-soaked appearance on lower leaves or water-soaked lesions (spots) on lower stems. Any plant part that is near or in contact with the soil may become infected. Infected plants yellow and wilt, often within days of infection, particularly when the weather is moist and warm (80 to 95F). Fruit rots, crown rots and root rots are also typical symptoms of the disease. Thick mats of white fungal threads (called mycelia) may grow from infected tissue, radiating from the plant onto the soil surface. Sclerotia (small spherical structures that are about the size of mustard seeds) develop on infected tissue and on the soil surface. Sclerotia range in color from light tan to dark reddish-brown to black. 041b061a72