Horticulture 2023 Newsletter
No. 16 April 25, 2023
https://hnr.k-state.edu/extension/info-center/newsletters/index.html
Blog Post: http://www.ksuhortnewsletter.org
Video of the Week: How to Sharpen a Mower Blade
https://kansashealthyyards.org/component/allvideoshare/video/how-to-sharpen-a-mower-blade?Itemid=101
REMINDERS
Do not remove foliage from spring-flowering bulbs until the foliage dies. You need to give time for the foliage to transfer energy to the bulbs.
Repot houseplants as needed. Go up 1 inch to 2 inches in size of pot.
Keep newly planted trees & shrubs watered as needed. Keep soil moist but not waterlogged.
K-State Garden Hour will present a webinar on drought tolerant plants on May 3. Details in next week’s newsletter.
TURFGRASS
Be on the Lookout for Sod Webworm on Tall Fescue Lawns
We have had numerous reports on tall fescue lawns that greened up this spring but have developed or are developing brown spots. In some cases this leaves the lawn with a pockmarked appearance or larger areas may be browned due to individual spots coalescing. We have found sod webworm damage on turf areas in the Frankfort, KS area (Marshall County) but individual turfgrass areas should be checked to confirm sod webworm as there can be other causes of turf problems. For example, we have also had reports of bronze cutworm damage or a warm-season grass greening up later than tall fescue.
If is very rare for sod webworm damage to show up at this time of year. I have only seen this once before in over 25 years of editing this newsletter.
Look for individual grass blades cut off at ground level. You may also find silken tunnels that the insects use to hide during the day. Large numbers of birds pecking holes in the lawn can also alert you to their presence. Most feeding takes place at night but they may feed during the day on overcast days. They can be especially active near dusk. Individual larva have a brown head capsule and spots down the side. See photo included in the web and blog versions of this newsletter.
Control measures should be considered when you find 2 to 4 webworms per square foot of sod. Irrigate (½ to ¾ inch) to bring the webworms close to the surface unless you can find them feeding. Treat in late afternoon or early evening when the insects are most active. Apply another 1/8 inch of water if possible to activate the insecticide. Suggested insecticides include bifenthrin (Talstar, Bug B Gon Max Insect Killer for Lawns, Ortho Insect Killer for Lawns Granules, Bug Blaster II) and cyhalothrin (Scimitar, Spectracide Triazicide). For more information, see https://hnr.k-state.edu/extension/horticulture-resource-center/common-pest-problems/documents/Sod%20Webworm.pdf . Many thanks to Jason Rugan of Rugan Lawn & Landscape for helping us ID this problem. Let me emphasize again that there can be other causes of turf decline so don’t assume you have sod webworm without checking for their presence. (Ward Upham)
Keep Mower Blades Sharp
Lawn-mowing season is here. Remember that dull blades give the lawn a whitish cast. A dull blade does not cut cleanly but rather shreds the ends of the leaf blades. The shredded ends dry out, giving the lawn that whitish look. A sharp mower blade is even more important when the turf starts putting up seed heads next month. The seed head stems are much tougher than the grass blades and more likely to shred. Under normal use, mower blades should be sharpened about every 10 hours of use. (Ward Upham)
Orchardgrass in Tall Fescue Lawns
Orchardgrass often infests tall fescue lawns. Unfortunately, orchardgrass is lighter green and faster growing than tall fescue, so it is very visible. Homeowners complain of the light green tufts of grass wherever this weed has become established. Even worse, there are no herbicides that will kill the orchard grass without also killing the turf. About the only good thing about orchardgrass is that it is a bunch grass and does not spread.
Orchardgrass often comes in as a contaminant in grass seed, especially K-31 tall fescue. Buying good grass seed is the first line of defense against this weed. Orchardgrass is a pasture grass and therefore is not found in the “weed seed” portion of the seed label. Rather, orchardgrass will be listed as “other crop seed.” Try to buy grass seed that has 0.0% “other crop seed.”
Control options are few and painful. Use glyphosate (Roundup, Killzall Weed and Grass Killer,
Kleeraway Systemic Weed and Grass Killer and others) to spot spray orchardgrass clumps. Any lawn grasses you hit will be killed, so keep the spots sprayed as small as possible. Wait until the spots have turned brown and then cut out the clumps and replace with a small piece of sod.
Large numbers of orchardgrass clumps may mean it is more practical to kill the entire lawn and
start over. This should be done in the fall rather than now.
For information on identification of orchardgrass, including images, go to:
http://kswildflower.org/grass_details.php?grassID=15 (Ward Upham)
FRUIT
Will I Have Peaches This Year?
If your peach trees were in bloom or had already formed fruit and you had freezing temperatures over the weekend, then likely not. Unopened buds are more cold tolerant. So how can you tell if your peach buds are still alive?
To check for low temperature injury to fruit buds or blossoms, use a sharp knife or razor blade and cut the bud in half longitudinally. If the area in the center is white to cream color and the style of the pistil is has not darkened then no damage has been done. But if the center in several buds or blossoms is dark brown or black, it has been killed. (Ward Upham)
Fertilizing Strawberries and Brambles
Most garden soils in Kansas have adequate levels of all nutrients other than nitrogen IF the area has been fertilized in the past. However, it is recommended that a soil test be done to be sure of the nutrient needs of your fruit planting. If the soil test recommends phosphorus and potassium, use a 10-10-10 fertilizer or 12-12-12 instead of what we recommend below but triple the rate. For example, instead of ½ cup per 10 feet of row, use 1.5 cups per 10 feet of row.
Strawberries (June-Bearing): June-bearing strawberries are not fertilized in early spring as this can make the berries soft and more prone to rot. Fertilize at renovation and again in late August to early September. In most cases, strawberries need primarily nitrogen, so the recommendations are for a high nitrogen fertilizer such as a 27-3-3, 29-5-4, 30-3-3 or something similar. Though recommended for lawns, these fertilizers will also work well for strawberries as long as they do not contain weed killers or crabgrass preventers. Apply ½ cup for every 10 feet of row. Note: For more information on renovating strawberries, see page two at http://www.bookstore.ksre.ksu.edu/pubs/mf598.pdf
Strawberries (Everbearing or Day-Neutral): Fertilize in the spring as growth starts and again in early August. Use the rates recommended for June-bearing strawberries. Everbearing (dayneutral) strawberries are not renovated.
Brambles (Blackberries and Raspberries): In most cases, brambles need primarily nitrogen, so use a high nitrogen fertilizer such as a 27-3-3, 29-5-4, 30-3-3 or something similar unless a soil test directs otherwise. Though recommended for lawns, these fertilizers will also work well as long as they do not contain weed killers or crabgrass preventers. Apply ½ cup for every 10 feet of row. Fertilize in spring as growth begins. (Ward Upham)
VEGETABLES
Asparagus Beetles
Be on the lookout for asparagus beetles. Both the adult and larvae of asparagus beetles feed on asparagus spears by chewing the tips and spear surfaces, leading to scarring and staining of the spear tips. Asparagus beetles overwinter as adults in trash near the garden. The adults are a blue/black beetle with a red prothorax with yellow spots. The larvae are a soft, greenish grub. Small, elongated, black eggs — sticking out long ways from the side of asparagus spears — are laid on developing spears.
Early control of beetles is important to reduce feeding damage later. Permethrin will provide control but requires a 3-day waiting period between spraying and harvest. Permethrin is found in Garden and Farm Insect Control and Eight Vegetable, Fruit & Flower Concentrate. (Ward Upham)
Rhubarb Harvest and Seedstalks
Rhubarb, like asparagus, is a perennial vegetable. It is harvested for the leaf stem, which is also called a petiole. Some years rhubarb will produce large, hollow-stemmed seedstalks that arise from the center of the plant. These should be broken or cut out as they appear so that energy will go into plant vigor rather than seed production. It will take several weeks for all the seedstalks to appear so be vigilant in removing them. Newer varieties of rhubarb are selected for vigor, bright red-colored stalks and less of a tendency to produce seedstalks than the older types. (Ward Upham)
Fertilizing Cole Crops
If you planted cole crops such as cabbage, broccoli and cauliflower earlier this spring, they will need a little fertilizer boost. These plants need to mature before summer heat arrives, so they must grow quickly while the weather is cool. A sidedressing of fertilizer about 3 weeks after transplanting helps plants continue to grow rapidly.
Use fertilizers high in nitrogen for sidedressing such as nitrate of soda or blood meal at the rate of 1/3 cup per 10 feet of row. You may also use lawn fertilizers that have close to 30 percent nitrogen such as a 30-3-4 or 29-5-4 but the rate should be cut in half to 3 tablespoons per 10 feet of row. Do not use lawn fertilizers that have weed killers or preventers. Fertilizer must be watered in if timely rains don’t do that job for you.
We have a sheet available that gives recommendations on how to sidedress specific vegetable
crops. It can be found at: https://tinyurl.com/yckz8v3w (Ward Upham)
Red Plastic Mulch and Tomatoes
Plastic mulches have long been known to provide advantages for the vegetable grower including earlier fruiting, increased yields and weed control. More recently advantages have been noted for colored mulches over the more traditional black plastic mulch. With tomatoes, the color of choice has been red. Though normally there is an increase in production of marketable fruit with red mulch over black mulch, the amount of the increase varies with the type of year we have. There may be no increase during years of near-perfect weather or up to a 20% increase with less favorable growing conditions. A good average expected increase is about 12%.
So, how do you apply plastic mulch? Commercial growers have a mulch-laying machine that applies the trickle (drip) irrigation line and the mulch in one operation. Home gardeners must do this by hand. The first step after soil preparation is to place a trickle line near the center of where the mulch will lay as the plastic will prevent rainwater or overhead irrigation from reaching the plants. Then construct trenches for the outer 6 inches of the plastic mulch. This allows the center of the bed to be undisturbed with the edges of the mulch draping down into the trench. Fill the trenches to cover the edges of the mulch. This will prevent wind from catching and blowing the mulch. If the soil has been tilled, a hoe is all that is needed to prepare the trenches. (Ward Upham)
PESTS
Termites or Ants
Both termites and ants are able to swarm and may have wings during part of their lives. Since these insects are close to the same size, people often misidentify flying ants as termites. Since flying ants do not attack wooden structures like termites, it is helpful to be able to tell the difference.
Fortunately, there are several differences that can easily distinguish the two. For example, ants have a thin waist; the waist of a termite is thick. Also, ants’ antennae are elbowed, while termites’ are curved. Thirdly, termites have two pairs of wings that are of equal length. Ants also have two pairs of wings, but theirs are of unequal length. Homeowners who find signs of termite activity should shop for a reputable pest control firm. (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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