Horticulture 2020 Newsletter
No. 31 August 4, 2020
https://hnr.k-state.edu/extension/info-center/newsletters/index.html
Blog Post: http://www.ksuhortnewsletter.org
Video of the Week: Composting: Making Black Gold
https://kansashealthyyards.org/all-videos/video/composting-making-black-gold
Reminders
- Divide iris if needed and you haven’t done so yet.
- Do not fertilize the warm-season turfgrasses, buffalograss, zoysiagras and bermudagrass, past August 15. Doing so may increase the chances for winter damage.
- Check mulch layers and add additional material if needed.
VEGETABLES
Still Time for a Salad Garden
Plant salad crops such as lettuce, radishes, spinach, turnips, mustard and other greens from mid-August to early September for a fall harvest. Plant slightly deeper than you did in the spring. This will keep the seed slightly cooler though still warm and the soil should retain moisture longer. Water frequently (if needed) until seedlings start to emerge — which should be fast with our warmer soils. Watering heavy soils can sometimes cause a crust to form. This can be prevented by a light sprinkling of peat moss, vermiculite or compost directly over the row. Reduce watering frequency after plants emerge. Plants may need to be protected from hungry rabbits and insects. (Ward Upham)
MISCELLANEOUS
Plants for Late Season Bloom
Landscapes are often drab this time of year. You can add interest to your home by planting shrubs this fall or next spring that flower later in the growing season. Consider one or more of the following.
Rose of Sharon (Hibiscus syriacus) is a tall shrub that produces single or double flowers. Colors range from white to red, purple or violet, or combinations, depending on the variety.
Crapemyrtle (Lagerstroemia indica) are dwarf-to-tall shrubs or trees. They are not reliably winter hardy in Kansas and often die back to the ground. Crapemyrtle flowers on new wood, so plants pruned (or killed) to the ground while dormant in late winter or early spring will bloom later the same year. Flower color varies from white, pink, to purple or deep red on different plants.
Bluebeard (Caryopteris x clandonensis) is also known as blue-spirea, blue-mist shrub, or caryopteris. It usually is found with blue flowers, but some cultivars have a bluish-violet to violet flower color. Plants are usually cut back in late winter or early spring. Flowers are borne on the current season’s growth.
Sweet Autumn clematis (Clematis terniflora) is a vigorous vine with large masses of small, white flowers that have a wonderful fragrance. Be careful with this one; it can easily outgrow its bounds. It is often a good idea to cut it back to the ground in early spring.
Davidiana clematis (Clematis heracleifolia var. Davidiana) is a bush-type clematis with small but interesting violet-blue flowers. Female plants bear interesting fluffy seed heads into the
winter. This clematis needs to be cut back to the ground each year to help maintain the shape of
the plant.
The PeeGee hydrangea (Hydrangea paniculata Grandiflora) is a somewhat coarse plant that develops large clusters of white flowers. It can be trained into a tree-like form. (Ward Upham)
Composting: The Science
Composting is a process whereby you can turn trash into treasure by recycling garden waste and kitchen scraps into humus that can improve soil structure and act as a fertilizer.
Microorganasims drive this process and are composed of bacteria, actinomycetes and fungi. Bacteria are composed of three different types that work best and different temperature ranges. Psychrophilic bacteria start the composting process and prefer the lowest temperature range and are most active at 55 degrees F. Their activity produces a small amount of heat so that the mesophilic bacteria can take over. Mesophilic bacteria prefer a temperature within the pile of 70 to 100 degrees. They are followed by the most heat-loving bacteria which are the thermophilic bacteria. They thrive at temperatures between 113 to 160 degrees F. These microorganisms die when they finish digesting the material in the pile and the temperature drops.
Actinomycetes are a special bacteria that are similar to fungi and molds. They are important as they help decompose some of the more resistant materials such as lignin and cellulose. They work best at moderate temperatures.
Fungi are less heat resistant and prefer temperatures between 70 and 75 degrees F. They are compost “finishers” and are most active after the other microorganisms are done.
So the compost pile goes through a process whereby the compost pile starts cool, builds up to a high temperature and then cools. Next week we will look at what we need to make a compost pile. For more information on compost pile microbes, see https://www.calrecycle.ca.gov/organics/homecompost/microbes (Ward Upham)
TREES
Tubakia Leaf Spot of Oaks
This leaf spot disease of oak is showing up in the Wichita area. Members of the red oak group are more likely to be affected than those in the white oak group, but members of both groups are showing symptoms. Red oaks often have distinct round spots as well as dead areas that follow the veins.
White oaks also have the dead areas that follow the veins and large blotches of dead tissue but lack the distinct spots. Leaves severely damaged may drop. However, trees rarely lose enough leaves to harm the health of the tree. No fungicide sprays are recommended. (Ward Upham)
PESTS
Peonies with the “Measles” and Powdery Mildew
The weather this summer has resulted in many peonies catching the “measles” and/or powdery mildew.
Measles: Measles is a disease, also known as red spot, that causes distinct, reddish-purple spots on the upper leaf surfaces. These spots often coalesce and become large, reddish purple blotches on the upper leaf surfaces but are a light brown color when viewed from the underside of the leaves. The spots on stems will merge and form streaks that are reddish brown.
Powdery Mildew: Plants infected with powdery mildew look like they have been dusted with flour and can lead to death of the leaves. This disease isn’t as common in Kansas than Measles but does show up at times.
Sanitation is the best control for both these diseases. Remove all diseased tissue, including stems, at the end of the growing season. Actually, all foliage can be removed in mid-August with no harm to the plants as the plants will be essentially dormant. Foliage that has already died should be removed now.
Mulch that contains plant debris should also be discarded and then replaced with fresh mulch. Reducing the source of the inoculum will reduce the chances of another severe outbreak next year. (Ward Upham)
Contributors: Ward Upham, Extension Associate
Division of Horticulture
1712 Claflin, 2021 Throckmorton
Manhattan, KS 66506
(785) 532-6173
For questions or further information, contact: [email protected] OR [email protected]
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Ward Upham
Extension Associate
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