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ANNOUNCEMENTS
K-State Garden Hour: Drought Tolerant Plants For A Challenging Kansas Landscape
https://hnr.k-state.edu/extension/consumer-horticulture/garden-hour/
The Kansas climate throws numerous extremes at our landscape plants. The most common climate extreme is periods of drought, which are difficult for both plants and gardeners. Join Jason Graves, Central Kansas District Horticulture Extension Agent, and Matthew McKernan, Sedgwick County Horticulture Extension Agent, as they address our climate challenges and provide suggestions for drought tolerant plants that will make gardening easier.
REMINDERS
• Harvest asparagus until spear size diminishes. Usually 6 to 8 weeks after first harvest.
• It is too early to spray for bagworms
• It is too late to spray for peach leaf curl
1. Start fruit spray schedule after petal drop.
2. Allow lawn to dry until see purplish areas in lawn before watering as this increases drought hardiness.
TURFGRASS
Fertilize Irrigated Cool-Season Lawns in May
Cool-season lawns such as tall fescue and Kentucky bluegrass should be fertilized this time of year if you plan to water throughout the summer. Lawns that aren’t irrigated through summer usually go through a dormancy period due to drought and do not require fertilization.
Spring brings about a flush of growth and by May this has tapered off for grasses making it an ideal time for fertilizing. Fertilizing in April could cause excessive shoot growth. Slow-release nitrogen sources are ideal as they promote controlled growth which is important during the summer as weather can be stressful to lawns.
Milorganite is an all-purpose, slow-release fertilizer that will feed your lawn nitrogen for eight to ten weeks after application. Other options in the retail market you may consider include cottonseed meal, alfalfa-based fertilizers and other plant/animal derived products. Bloodmeal is an exception as the nitrogen is released quickly. These fertilizers are natural and organic with typically less than 10 % nitrogen by weight. Compared with most synthetic fertilizers you will need to apply more product to get the same amount of nitrogen. Apply enough fertilizer to give the lawn one pound of nitrogen per 1,000 square feet. For example, if the fertilizer is 6% nitrogen by weight you will need to apply almost 17 pounds of fertilizer product per 1,000 square feet.
Fertilizers that have only a portion of nitrogen available as a slow-release can be used as well by following the label directions. Quick release fertilizers, which are less expensive, can be used if you apply it in two doses. Give the lawn 0.5 pounds of nitrogen per 1,000 square feet in May and again in early June. (Cynthia Domenghini)
VEGETABLES
Sweet Corn Primer
Improvements to the standard sweet corn has resulted in more choices available to the homeowner which can bring some confusion over which type of corn is ideal for your location. Here is an overview of some types you may encounter as you make your decision.
Standard (su): This original sweet corn has a “sugary gene” (su) and should be grown isolated from field corn, popcorn, supersweets and ornamental corn by growing it at least 200 to 250 feet away or have a difference of 12 to 14 days in time to maturity. This will prevent cross-pollination. When the soil temperature reaches at least 55 degrees F it is time to plant. Recommended varieties include: Honey and Cream, Silver Queen, Sterling Silver, Jubilee or Merit.
Supersweet (sh2): The sh2 gene in supersweets provides up to three times the sweetness of standard sweet corns. They also hold their sweetness longer after harvest. However, the kernels tend to be tougher and have less of the good “corn” flavor. Supersweets should be grown in isolation from other sweet corns and are very sensitive to cooler soils. Plant when the soil temperature reaches 65 degrees F. Varieties to try: Candy Store, Florida Staysweet, Sugar Loaf, Sweet Time or Sweetie.
Sugar Enhanced (se): Tender kernels, flavor and tolerance of cooler soils make this a popular choice of sweet corn. The “se” gene gives this corn its sweetness which holds longer post-harvest than the standard but not as long as the supersweets. Varieties are identified as “se+” or “se se” if both parents were “se” types. If only one parent was an “se” type and the other was a “su” type, then the variety will be listed as “se”. Isolation is not necessary when growing this type of corn. Suggested varieties: Bodacious, Ambrosia, Sweet Temptation, Delectable and Miracle.
Triplesweet (synergistic): A combination of the “su” and “se” types, Triplesweet brings the best of both types of sweet corn. These should be planted later than standard types due to intolerance of cool soil. Varieties to consider include: Serendipity, Polka, Avalon and Frisky. (Cynthia Domenghini)
Delay Planting Winter Squash and Pumpkins
There are several reasons to delay planting winter squash and pumpkins until mid-June. If planted in early May, along with other warm-season crops, squash and pumpkins will mature early enough to attract first generation squash bugs in July. Additionally, a later planting will allow the fruit to mature closer to Halloween avoiding long-term storage.
Check out our publication on squash bugs for more information on how to protect your plants from the second generation in August. (Cynthia Domenghini)
FRUIT
Fruit Sprays and Spray Water pH
Captan is the most common fungicide used in fruit tree sprays, but this product is subject to alkaline hydrolysis. In this process certain pesticides break down if mixed with water that has a high pH. If you mix your spray of captan with
5 gallons of water that has a pH of 7, the captan will break down so only half of it will be available in 8 hours. If the pH of the water is 10 the captan will break down in 2 minutes.
Malathion is hard to find, though it once was the most common fruit pest control insecticide. Malathion will also break down if the pH of the water is high, but not as easily as captan. It is stable at a pH between 5 and 7. Lambdacyhalothrin is found in Bonide Fruit Tree and Plant Guard and is also stable between a pH of 5 to 7.
Not all pesticides are susceptible to alkaline hydrolysis. Check out this resource, distributed by Cornell University, for more information about pesticide sensitivity to alkaline hydrolysis.
If your water pH is too high, food grade citric acid can help. With a pH of 8, add 2 ounces of citric acid per 100 gallons of water (1 ¼ teaspoons per 10 gallons) to bring the pH down to about 5.5. Contact your local Extension office for instructions on how to test the pH level of your water. Here is a map from our K-State Research and Extension website to help you locate your local county Extension office. (Cynthia Domenghini)
PESTS
Bagworms, It’s Still Too Early to Spray
As you see bagworms appearing, handpicking can be an effective method of control. As the numbers increase, manual removal becomes impractical and spraying is recommended. Although new bagworms tend to hatch and leave the bag in May, spraying is not recommended until June. If sprayed too soon, while the worms are still protected inside their mother’s bag, the control measures are ineffective and wasted. Here is an article for those who cannot wait to spray until June. (Cynthia Domenghini)
Poison Ivy Identification and Control
Everyone knows why being able to accurately identify poison ivy is important. It may be less well known that poison ivy grows in various forms: erect woody shrub, climbing woody vine and as a groundcover. To further complicate identification, the leaves of poison ivy can also vary.
In the vining habit, aerial roots give the vines a fuzzy, rope-like appearance. As a groundcover, poison ivy is often confused with Virginia creeper or Woodbine. Poison ivy shrubs can appear in fields, pastures, woods or even the home garden. Leaf margins may be toothed, incised, lobed or smooth, but will always appear in groups of three. The leaf size can vary, but the middle leaflet is the only one with a long stalk and is larger than the other two. The other two leaves are closely attached to the petiole (leaf stem).
To eradicate poison ivy, begin by covering your body with pants, long sleeves and gloves. Once finished, wash all your clothing and your body to remove any traces of the plant’s toxins. In the ground cover form, direct spray or grubbing (digging) are common strategies for removal. Make sure the soil is moist before grubbing out the plants including the root systems.
Direct spray is a common control method for poison ivy in the shrub form. Triclopyr (Brush-B-Gon Poison Ivy Killer, Brush Killer Stump Killer) is popular for poison ivy control. Glyphosate (Roundup; Killzall Weed and Grass Killer; Nutgrass, Poison Ivy and Vine Killer) or dicamba are also effective herbicides for this purpose. For woody vines of poison ivy, cut the plant off at the base and treat the emerging sprouts with herbicide when they appear.
Repeat applications of herbicide are usually necessary as this can be a tough plant. (Cynthia Domenghini)
Blackspot of Roses
Blackspot is a common disease of susceptible rose varieties. This fungal disease presents dark, circular lesions with feathery edges on the top surface of the leaves as well as raised purple spots on young canes. Infected leaves often turn yellow between the spots and drop. The infection usually begins on lower leaves working its way up the plant. High relative humidity (>85%), warm temperatures (75-85 degrees F) and wet leaves (6+ hours of wetness) are ideal conditions for blackspot. New leaves are the most vulnerable.
Blackspot can survive on fallen leaves or canes and spreads through splashing water. Following proactive cultural practices can prevent blackspot from entering your rose garden.
1.) Plant roses that are resistant to blackspot. Here is a resource from Purdue University that offers suggestions.
2.) Use drip irrigation and/or water carefully to keep droplets off the leaves.
3.) Plant roses in sunny locations with good air flow so wet foliage can dry quickly.
4.) Remove fallen, diseased leaves and prune out infected canes to reduce the spread of the disease.
A regular spray program can be used to protect your plants using a 10 to 14 day schedule of fungicides. Recommended fungicides include: tebuconazole (BioAdvanced Disease Control for Roses, Flowers and Shrubs, BioAdvanced All-In-One Rose and Flower Care), myclobutanil (Immunox, F-Stop Lawn and Garden Fungicide) and chlorothalonil (Broad Spectrum Lawn and Garden Fungicide, Garden Disease Control, others). (Cynthia Domenghini)
Contributors: Cynthia Domenghini,. Instructor
Division of Horticulture
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