Blog Posts - K-State Horticulture Newsletter

Plants for Late Season Bloom

8/3/2020

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

8/3/2020

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)

Tubakia Leaf Spot of Oaks

8/3/2020

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)

Peonies with the "Measles" and Powdery Mildew

8/3/2020

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)

Spider Mites on Tomatoes

7/27/2020

Watering Newly Planted Trees and Shrubs

7/27/2020

Newly planted trees have not established the extensive root system needed to absorb enough water during hot, dry, windy summers. Even trees two or three years old should receive special care.

Deep, infrequent watering and mulching can help trees become established. Newly transplanted trees need at least 10 gallons of water per week, and on sandy soils they will need that much applied twice a week. The secret is getting that water to soak deeply into the soil, so it evaporates more slowly and is available to the tree’s roots longer. One way to do this is to drill a 1/8" hole in the side of a 5-gallon bucket and fill it with water. The hole should be near the bottom of the bucket. Let the water dribble out slowly next to the tree. Refill the bucket once after moving it to the opposite side of the tree. After this bucket empties, you have applied 10 gallons. Very large transplanted trees and trees that were transplanted two to three years ago will require more water.

A perforated soaker hose or drip irrigation can be used to water a newly established bed or foundation planting. In sunbaked soil, you may need to rough up the surface with a hoe or tiller to get water to infiltrate easily. It may be helpful to set the kitchen oven timer, so you remember to move the hose or shut off the faucet. If you are seeing surface runoff, reduce the flow, or build a berm with at least a 4-foot diameter around the base of the tree to allow the water to percolate down through the soil, instead of spreading out.

Regardless of method used, soil should be wet at least 12 inches deep. Use a metal rod, wooden dowel, electric fence post or something similar to check depth. Dry soil is much harder to push through than wet. (Ward Upham)

Watering Fruit Plants During the Summer

7/27/2020

When temperatures exceed 90 degrees F, fruit plants lose water quickly. When this happens, moisture is withdrawn from the fruit to supply the tree. Stress from high temperatures, along with a moisture deficit in the root environment, may cause fruit to drop or fail to increase in size. The stress may also reduce the development of fruit buds for next year's fruit crop.

If you have fruit plants such as trees, vines, canes, and such, check soil moisture at the roots. Insert a pointed metal or wood probe such as a wooden dowel, piece of rebar or a electric fence post to check the depth of watering. Even a long screwdriver works well for this. Push these into the soil with the goal of reaching 8 to 12 inches. This may not be possible if the soil is hard and dry. If you cannot reach the recommended depth, the plants should be irrigated to prevent drooping and promote fruit enlargement. Water can be added to the soil using sprinklers, soaker hose, drip irrigation, or even a small trickle of water running from the hose for a few hours. The amount of time you irrigate should depend upon the size of plants and the volume of water you are applying. Add enough moisture so you can easily penetrate the soil in the root area to the recommended depth. When hot, dry weather continues, continue to check soil moisture at least once a week.

Strawberries have a shallow root system and may need to be watered more often – maybe twice a week during extreme weather. Also, newly planted fruit trees sited on sandy soils may also need water twice a week. (Ward Upham)

Inexpensive Method of Watering Trees

7/27/2020

We mentioned in an accompanying article about using a soaker hose to water trees. We thought it might be helpful to provide more details.

Soaker hoses are notorious for non-uniform watering. In other words, you often receive too much water from one part of the hose and not enough from another. On small trees, circling the tree several time with the soaker hoses will even out the amount of water applied but this isn’t practical for larger trees. Hooking both the beginning and the end of the soaker hose to a Y-adapter helps equalize the pressure and therefore provide a more uniform watering. The specific parts you need are shown in the photo above and include the soaker hose, Y-adapter and female to female connector.

It is also helpful if the Y-adapter has shut off valves so the volume of flow can be controlled. Too high a flow rate can allow water to run off rather than soak in.

On larger trees, the soaker hose can circle the trunk at a distance within the dripline of the tree but at least ½ the distance to the dripline. The dripline of the tree is outermost reach of the branches. On smaller trees, you may circle the tree several times so that only soil which has tree roots will be watered.

Soil should be wet at least 12 inches deep as 80% of a trees roots are in the top foot of soil. Use a metal rod, wooden dowel, electric fence post or something similar to check depth. Dry soil is much harder to push through than wet and your probe will stop when it hits dry soil. How long it takes water to reach a 12 inch depth varies depending on the rate of water flow and soil. Record the amount of time it takes to reach 12 inches the first time the tree is watered. After that, simply water for that same amount of time. (Ward Upham)

Crabgrass Control

7/27/2020

This is the time of year when people really notice crabgrass infestations. By far the best way to control crabgrass is to prevent it by maintaining a good, thick lawn. Crabgrass is an annual that must come up from seed each year and the seed must have light in order to germinate. If a lawn is thick enough that sunlight does not reach the soil, the crabgrass will not germinate. Under Kansas conditions it is not easy to maintain such a lawn; so many gardeners do the next best thing and apply a crabgrass preventer in the spring. Crabgrass preventers kill the seed as it germinates. Most do not have any effect on crabgrass that has already come up. If we are too late to apply a preventer, we do have other herbicides that will kill crabgrass plants including Ortho Weed-B-Gon Max +Crabgrass Control, Fertilome Weed-Out with Crabgrass Control, Monterey Crab-E-Rad and BioAdvanced Lawn Weed & Crabgrass Killer. Each contains quinclorac, which is a crabgrass herbicide, as well as other active ingredients that control broadleaf weeds. Quiclorac is an excellent crabgrass killer that controls not only crabgrass but also has good activity on foxtail and certain broadleaves such as field bindweed, black medic and clover. However, it does little to nothing to goosegrass.

Fortunately, crabgrass starts declining about the middle of August. This is about the same time that cool- season grasses such as tall fescue and Kentucky bluegrass start to come out of their summer doldrums. By the first of September, the crabgrass will be less noticeable. Therefore, a small infestation is best ignored. Remember that crabgrass is a warm-season annual and will be killed by the first frost. (Ward Upham)

Wood Chips As Mulch

7/27/2020

With many municipalities and tree service companies having wood chippers now, gardeners often are able to get chips free. We are sometimes asked our opinion about whether these make a good mulch.

Some people have heard that these chips will tie up nitrogen so that the garden plants won't grow as well. If wood chips are used as a mulch, there is no cause for concern. However, if the chips are mixed with the soil, there can be a problem during the breakdown process. The microorganisms that break down the chips need a certain amount of nitrogen during the process. With most green material, there is enough nitrogen in the material itself to meet the needs of the microorganisms. However, nitrogen levels in wood chips are so low, the microorganisms must borrow it from the surrounding soil. This results in less nitrogen being available to the plants. However, when the raw organic material has been digested, the microorganisms die and release the nitrogen. Therefore, the nitrogen is not lost but is simply unavailable for plant use for a period of time. Again, this is only a concern if the wood chips are mixed into the soil. There is no problem with nitrogen tie-up if the chips are used as a mulch.

However, one point should be kept in mind. These chips can be used by foraging termites as a bridge to homes and other structures. Termites are light and heat sensitive and will not bother the chips themselves if they are 3 inches deep or less. Therefore, watch the depth of these chips near the house or other buildings. Also leave a bare area several inches wide next to the house so that any termite activity is noticeable. (Ward Upham)