Welcome to the Sargent County Gardening Corner | |
Brought to you by NDSU Extension--Sargent County, the Sargent County Gardening Corner is a horticulture newsletter which aims to be an educational resource and to highlight the North Dakota horticulture, agriculture and gardening challenges and successes in our area. Please feel free to contact me with topics you would like to see covered in the future.
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Melissa Seykora
NDSU Extension Agent
Agriculture & Natural Resources
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In This Issue:
- Pause on Fertilizing
- Pause Watering Trees
- Scab on Potato
- A Reminder About Preharvest Intervals
- Impacts of Fluctuation Precipitation in Vegetables
- Fire Blight of Fruit Trees
- Fall Webworms in Trees
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Lawns are not hungry now. It's best to wait until early September when temps cool off and lawns get invigorated. Stop fertilizing trees and shrubs, including roses. We do not want to stimulate new growth, which will be succulent and subject to injury over winter. | |  |
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Pause Watering Trees
August is typically the driest month of the summer. As we move through the summer we are depleting our subsoil moisture and it is common to think that our trees will need to be watered more frequently. This is not the case for trees. Start hardening off your newly planted trees by watering them less frequently beginning in the month of August. This will help the trees to start preparing for the long winter ahead. If the trees have too much moisture going into winter they may have a harder time surviving. Once we have hardened off the trees for a period of time towards the end of summer we will want to give them a final good watering heading into fall before freeze-up.
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Bacteria create scars on tubers. Peel off scars. In future, prevent scab by keeping soil evenly moist for 4–6 weeks after flowers appear. Avoid fresh manure. Rotate crops. Use certified seed and resistant varieties. Among early reds, ‘Norland’ is better than ‘Red Pontiac’. | |
A reminder about preharvest intervals | |
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When spraying for insects, remember to pay attention to preharvest intervals. The preharvest interval (PHI) refers to the amount of time you need to wait before applying an insecticide and harvesting. Applying too early is against the law, and it puts your customers at risk. You usually have to search for this information on the label, because the PHI can be different for different crops. Check the label for the crop you're growing, and you'll find the PHI and other important information about application rates.
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Impacts of fluctuating precipitation on vegetables | |
Whenever we have a lot of rainfall following weeks of drought, we can anticipate some changes in our crops. Fluctuating water levels are behind a range of issues like cracking and blossom end rot in tomatoes, blossom end rot in peppers and summer squash, hollow heart in potato, and hollow stem in broccoli. Expect to see at least some of these issues in the coming week, particularly cracking in tomatoes, which occurs after tomatoes receive a flush of moisture following dry conditions.
One thing I've noticed is that after a long period with rain, farmers are anxious for things to dry out again in order to get back into the fields, or may skip a round of irrigation. Keep track of soil moisture in the coming week to make sure your soil doesn't dry out too much.
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Fire Blight of Fruit Trees | |
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Fire blight is one of the most devastating and difficult-to-control diseases of many fruit trees, including apple and pear, as well as of other rosaceous ornamental plants.
The first symptoms of fire blight occur in early spring when temperatures are above 60 °F and the weather is rainy or humid. Infected flowers turn black and die. The disease moves down the branch, resulting in death of young twigs. These blacken and curl over, giving the appearance of a “shepherd’s crook.” Leaves on affected branches wilt, blacken, and remain attached to the plant, giving it a fire-scorched appearance. Slightly sunken areas, called cankers, appear on twigs, branches, and the main stem. The cankers initially have a water-soaked appearance, but then become sunken and dark. Cracks may appear in the bark around the cankers. The bacteria survive in the cankers. Many parts of the plant can be affected, including blossoms, stems, leaves, and fruit. During wet spring weather, there may be a milky-like, sticky liquid oozing from the infected plant parts, and it contains the bacterial pathogen. Insects and splashing rain can then spread the disease.
There is no cure for fire blight, making disease prevention extremely important. Controls for fire blight include selecting tolerant varieties, using recommended cultural practices and sanitation measures, and applying insecticides. Although these methods are not 100 percent effective, they help reduce disease severity. Prune out blackened twigs and branches with cankers during the dormant season. Pruning during the growing season may spread the disease.
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Fall webworm caterpillars may feed on more than 100 species of deciduous forest and shade trees. Preferred hosts include mulberry, walnut, hickory, elm, sweetgum, poplar, willow, oak, linden, ash, apple, and other fruit trees.
The adult moths are about 3/4 inch long. The wings are all white or white with black spots. Mature larvae are about 1 inch long and may occur in two color forms: those with black heads are yellowish-white, and those with red heads are brown. Both color forms have paired black tubercles running down the back. They are covered with long, silky gray hairs.
The caterpillars produce a web of fine silk over terminal branches. They only feed inside the web, which they enlarge as they grow. Look on the south side of tree crowns for the first sign of webbing. The webs may become messy, but the caterpillars rarely consume enough terminal growth to affect the tree. The first generation begins in May and is usually small. The second-generation caterpillars are present from August through October. The dry webs hang on terminals into the winter.
Knock down the tents with a stick or a blast of water or prune out webbed terminals as they are detected. Usually they will not harm the trees, but in large infestations the following insecticides can be used:
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Bt (Bacillus thuringiensis, var. Kurstaki)
- horticultural oil
- insecticidal soap is recommended to control young larvae in large infestations to protect beneficial insects.
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Lawn, Garden, or Tree Questions??? |
We are here to help you answer any lawn, garden or tree questions.
- What are all of these dead spots in my lawn?
- Why is my lawn yellow?
- What happened to my peas?
- What insect is eating my broccoli?
- Did my tree survive the winter?
- What are these spots on my trees?
These are all common questions and your NDSU Extension Agent can help you in diagnosing the problem and finding a solution!
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