Master Gardener Tips: Using straw for mulch

Chris Himmelwright
Pratt Tribune
Wheat straw is a good choice for summer garden mulching options.

Mulching Garden Crops

Now is a good time to mulch garden vegetables if you haven’t done so already. Mulches provide several benefits including weed prevention, reduced watering due to less evaporation and cooler soils that enhance root growth. Straw and hay are popular mulches in Kansas due to their availability. However, both may contain weed seeds that will germinate if the thatch layer is not thick enough.

Better than hay, straw is the dry hollow hay stalks remaining after cereal crops such as wheat or barley have been harvested they contains few or no seed heads, especially when compared to hay.”  (University of Maryland Extension Service). Straw stalks don’t compact or mat.  They’re also slow to decompose and don’t tie up nitrogen or other nutrients in soil, making the perfect mulch.

Grass clippings can also be used if the lawn has not been treated with weed killers. Add only a thin layer of clippings at a time and allow to dry for 2 to 3 days before adding more. A thick layer will form a mold that is almost impervious to water. A mulch layer one-half to three-quarters inch thick is about right for grass clippings but hay or straw should be at a depth of 2 to 4 inches.

Strawberry Bed Renewal

Next year's strawberry crop will be affected by what you do to this year's strawberry bed. The sooner after harvest the patch is cleaned up, fertilized and irrigated, if possible, the better the chance of getting a good crop next year. One of the main goals in renovation is to provide a high level of sunlight to plant leaves so they can manufacture the food the plant needs. If leaves have disease spots, remove all the leaves in the bed. Removing, these diseased leaves and weeds will cause new, non-diseased leaves to develop and remove competition from weedy plants. Hedge shears or even a mower can be used. Be sure the mower blade is high enough to avoid the strawberry crowns. It is also important to reduce the number of strawberry plants so they do not compete for light, moisture and nutrients. If you have a small bed, you can hoe out or pull some plants so they are spaced about 4 to 6 inches apart. On large beds, adjust a rototiller so you can till between the rows, and cut each row back to about 10 inches wide. The next step is to fertilize the plants with about 3/4 to 1 pound (3 to 4 cups) of a complete fertilizer such as 13-13-13 (nitrogen, phosphorus and potassium) or an equivalent on each 25 feet of row. If a soil test shows adequate levels of phosphorus and potassium, use 3/4 pound (1.5 cups) of a 16-0-0 (nitrate of soda) fertilizer per 25 feet of row instead. If nitrate of soda is unavailable, use the lawn fertilizer that contains about 30% nitrogen such as a 30-0-3, 28-0-3 or something similar.

Make sure the lawn fertilizer does not contain a weed killer or preventer. These fertilizers should be used at the rate of 3/4 cup per 25 feet of row. The next step is to irrigate to wash the fertilizer into the soil and provide moisture for the rapid growth of the strawberry plants. When the soil is dry, apply about 1 inch of water. A garden sprinkler can do a good job applying the water. Controlling weeds and watering throughout the summer are important so plants are vigorous when fruit buds begin to develop in September and October.

Sweet Corn Earworm

Corn earworm tends to be a problem every year on sweet corn in Kansas. The earworm moth lays eggs on developing silks at night. When the egg hatches, the larva crawls down the silk and into the ear. Feeding starts at the tip of the ear and works down. Though several earworms may hatch and attack a single ear, only one is usually present at harvest due to the cannibalistic nature of the insect. Control is challenging as silks continue to grow over a period of time. This means that even if silks are treated, new silk will appear that hasn't been protected. Applications every 2 to 3 days are needed for insecticides to be effective, especially in early July when peak flight of these moths usually appear.

There is a three-week period from silking to harvest, but there is only a two-week period from when the silks appear to when they begin to dry. Since moths prefer juicy silks and shun those that have started to dry, insecticides are only needed the first two weeks of silking. Homeowners can use cyfluthrin (Baythroid; Bayer Vegetable and Garden Insect Killer) or spinosad (SpinTor; Captain Jack's Dead Bug Brew; Conserve; Borer, Bagworm, Tent Caterpillar & Leafminer Spray). Spinosad is an organic product. Commercial growers have additional choices including zeta-cypermethrin (Mustang Max), bifenthrin+zeta-cypermethrin (Hero), spinetoram (Radiant) and flubendiamide (Belt). Though more time consuming, mineral or other light horticultural oils may also be used as an organic control. The oil is placed inside the silk end of the ear with a medicine dropper (½ to 3/4 of a dropper) when the tips of the silks begin to wilt and turn brown. This will coat the earworms already present and likely suffocate them and earworms that enter the ear after the mineral oil is applied will also be controlled. Applying the oil before the silk has begun to brown may interfere with pollination, leading to incompletely filled ears.

*Adapted from the Kansas State Horticulture Newsletter.