In the Vegetable Garden-July

In the Vegetable Garden-July

  • By Cleve Campbell
  • /
  • July 2018 - Vol.4 No.7
  • /
  • 0 Comments

If you live in Central Virginia and like rain, you would have loved the month of June! Now we gardeners love rain but too much of a good thing can cause problems. During the month of June we received more than twice the amount of rain as normal.

Wet weather and plants are usually a match in heaven. However,  too much of a good thing can be bad for our vegetable gardens,  especially if the soil becomes waterlogged and stays that way, as poorly-drained clay soil tends to do.   All that water can cut off the air supply to the plants’ roots and to the microoranganisms that live in the soil. It can lead to root rot. In addition to root problems caused by excessive rain, wet weather can cause diseases via bacterial and fungal pathogens fostered by long term moisture on foliage and root systems.

There are two tomato plant diseases that are expected to do very well this summer because of the abundance of rainfall we had in June: early blight and septoria leaf spot.

Early Blight spots. Note concentric rings in a bull’s eye pattern that can be seen in the center of the grayish blotch.
Photo: Paul Bachi, University of Kentucky, Bugwood.com

 

 Early blight is caused by the fungus Alternaria solani, and it is common in Virginia. It occurs to some extent every year wherever tomatoes are grown. Don’t be confused by the name “early” as the disease may occur at any time during the growing season. Early blight causes irregular, brown leaf spots (lesions) that range in size up to ½ inch in diameter.

 

 

The most important diagnostic indicator of Early Blight is the formation of dark, concentric rings within the lesion, giving the spots a target-like or bull’s eye appearance, and often causing the leaf to turn yellow, dry up, and fall off. The lesions initially appear on the lower, older leaves near the base of the plant and can progress rapidly up from the lower foliage to new growth during wet weather.

Early Blight
Photo: Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org

 

Septoria Leaf Spot is caused by the fungus, Septoria lycopersici, characterized by several small, gray, round leaf spots with dark borders. A few black, pinhead dots may be seen within the spots.

As with Early Blight, the spores survive in residues from diseased plants. Septoria leaf spot can occur anytime during the growing season. Septoria leaf spot disease first develops on the older leaves nearest the ground and continues upward on new leaves as the growing season progresses. Heavily-infected leaves may scorch and wilt, giving the plant the appearance of a wilt disease. The fruits are rarely infected; however, the leaf loss reduces fruit yield and quality, and the exposed fruits are more susceptible.

Septoria Leaf Spot. Note the white pin head in middle of spot. Photo: Bruce Watt, University of Maine, Bugwood.com

 

For more information on Early Blight, Septoria leaf spot and other tomato diseases check out our Garden Shed article Tomato Diseases.

Here is our list of July vegetable gardening tips and tasks:

July in the vegetable garden is primarily a month of maintenance: watering, applying additional mulch, weeding, and harvesting.  The ambitious gardener may take on additional tasks, such as sequential planting of select vegetables, and planning and preparing for the planting of fall crops.

July is a good month for filling in empty spaces left from those early-spent spring crops such as lettuce, English peas, potatoes, and radishes. July planting may include beans and squash and a host of other vegetables. Take a look at the handy-dandy chart below, which was developed using the Virginia Cooperative Extension Publication 426-331 “Vegetable Planting Guide and Recommended Planting Dates.”

Not sure of what varieties or cultivars of vegetables to plant? A comprehensive list of recommended vegetables for Virginia can be found in the Virginia Cooperative Extension Publication, “Vegetables Recommended for Virginia”, now available from the Fluvanna County Extension Office.

Weeding

It’s important to control weeds around vegetables because weeds will out-compete vegetable plants for nutrients, water, and sunlight. The best method to control weeds is by mechanical extraction, meaning good old-fashioned weed-pulling or the use of a hoe. For small weeds, the “hoop” or “stirrup” hoe is highly recommended because it allows for shallow cultivation.  Another plus for the hoop hoe: it doesn’t  bring weed seeds to the surface of the soil! Many weed seeds require sunlight to germinate, so deep cultivation or utilizing a tiller often brings seeds to the surface of the soil, facilitating seed germination for a new crop of unwanted weeds.

Hoop or Stirrup Hoe

More Tips and Tasks for July:

  • To save space in your garden, construct temporary or permanent woven wire fences which will provide vertical support for runner varieties of beans, as well as for cucumbers. Plants can be trained to climb the fence, both saving space and making harvesting easier since the vegetables will be hanging at a convenient height.
  • A Threat to Basil is a fungal disease specific to sweet basil called fusarium wilt of basil. The fungus attacks the water-conducting tissue (xylem) within the stem. Infected plants will grow normally until they are six to twelve inches tall. Then the plants become stunted and will suddenly wilt. The stem may become curved, often referred to as a shepherd’s crook, and there will be brown streaks along the stems. Once established, the fungus can over-winter and survive many years in the form of spores, ready to cause new infections of basil or other members of the mint family that are planted in the same area. Currently, there is no fungicide approved for the treatment of this fungal disease, but it can be controlled somewhat by removing all diseased plants, by avoiding planting basil in the same location, and by planting disease-resistant varieties. Additional information on fusarium wilt of basil is available at ncsu.edu/-fusariumbasil
Fusarium wilt of basil (Fusarium oxysporum f. sp. basilicum)
Debbie Roos, NCSU Agricultural Extension Agent, Chatham County, NC

Fusarium wilt of basil (Fusarium oxysporum, f. sp. basilicum).  Photo: 
Debbie Roos, NCSU Agricultural Extension Agent

  • Pepper plants are more productive if given appropriate moisture. Placing mulch (such as wood chips or leaf mulch) around plants will help retain soil moisture and reduce the need for frequent watering. In addition to conserving water, mulch provides the extra benefit of being a weed barrier.

Continue to monitor water moisture levels around plants. The rule of thumb is that plants need one inch of water per week to maintain productivity.  Mulching reduces the need for frequent watering and improves yields. Early morning is the best time to water. Evening watering is less desirable because leaves that remain wet through the night are more susceptible to fungal diseases.

  • Okra blossoms are one of the showiest blooms in the vegetable garden but they only last one day. Keep your eyes peeled if you don’t want to miss them. If the flower has been pollinated, a miniature okra pod can be seen beneath the wilted flower.
  • Wondering if your blueberries are ripe enough to pick? Just try pulling a few berries from the stems. If they come off easily, they are ready to harvest. If not, they need to ripen more. Cover with netting or the birds will beat you to the fruit.
  • Dry weather causes Swiss chard to bolt or prematurely go to seed. Water your plants to extend the season.
  • Cucumbers develop a bitter taste if the soil is not kept consistently moist. Leaf mulch will help maintain soil moisture.
  • Harvest cucumbers for pickling when they reach 2-4 inches in length; for table use, harvest when no longer than 5-6 inches. Remove any over-ripe cucumbers to encourage continuous production.
  • Withhold water on potatoes when the plants begin to die down. Water and fertilizer may disturb the dormancy stage and cause regrowth, and may also cause potatoes to crack.
  • If potatoes are visible along the soil surface, they probably look green. This coloration is caused by exposure to light. Green-skinned potatoes will taste bitter. Avoid this problem by covering potatoes with soil or mulch to protect them from the light.
  • Pumpkin and squash blossoms are both beautiful and edible. To prepare squash or pumpkin blossoms for an appetizer, pick them after they open. Wash and drain the blossoms to remove insects and dirt, dip them in a flour or beer batter, and fry until golden.
  • Although tomatoes are self-pollinating, they need movement to transfer pollen. If it is hot and calm for several days, gently shake plants to transfer pollen and assure fruit set. Hot temperatures can also interfere with blossom set.
  • Shredded Chinese cabbage is a good hot weather substitute for lettuce in salads and sandwiches. A second crop may be started now for fall harvesting.
  • In the summer, dry soil may become hard, making it difficult to work and inhibiting seed germination. Plant your succession and fall vegetables when the soil is moist, either after a rain or after watering the area thoroughly the day before you plant. Seeds may be planted in a shallow trench to conserve moisture.
  • Did you know? Daytime temperatures above 90º F. prevent snap bean flowers from developing.
  • Too many cucumbers, zucchini, or tomatoes? Think pickles, relishes, and tomato sauces.
  • Don’t forget the County Fair! Show off you gardening abilities by exhibiting fresh vegetables, flowers, and fruits.

Thanks for stopping by The Garden Shed. We hope to see you again next month!

Sources:

“ Vegetable Planting Guide and Recommended Planting Dates,” Virginia Cooperative Extension Publication No. 426-331, pubs.ext.vt.edu/426/426-331

“Weeds in the Home Garden,” Virginia Cooperative Extension Publication No. 426-364, pubs.ext.vt.edu/426/426-364

“Basil Problem,” NC Cooperative Extension, https://growingsmallfarms.ces.ncsu.edu/growingsmallfarms-fusariumbasil/

 

 

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