Squash bug control

Squash plants are target for bugs, disease

Bill Sevier: Ask a Master Gardener

Saturday, April 23, 2016

Q: I lost my squash last year to squash bugs. How can I prevent them from destroying my plants this year? Troy, Tulsa

A: Squash is popular in the vegetable garden, and insects and disease represent the major challenge to successful production of fruit.

Three main insects are problems for these vegetables — squash bugs, squash vine borers and cucumber beetles. They are also problems to varying degrees for other vegetables in the cucurbit family (squash, cucumbers, melons, cantaloupe and pumpkins).

Squash vine borers attack the vines at their base; squash bugs suck sap from leaves causing them to develop yellow to brown spots and often wilt, especially in young plants. Cucumber beetles do little feeding damage but can infect the plants with a bacterial wilt disease.

OSU has been involved with studies to investigate control methods. One study involved floating row covers to exclude squash bugs. Row covers are thin, lightweight synthetic material allowing sun and rain to enter but keeping insects out. Covers were put in place at time of planting and removed at various intervals after 50 percent of the plants had female blossoms (ones with tiny fruit at their base). Since squash must be pollinated by insects, the covers were removed to allow bees and other pollinators to visit the blossoms.

The study showed row covers did reduce, but not eliminate, the need for insecticides. The covers also protected plants from hail and winds but delayed early harvest. However, later harvest was extended. A downside was that covers were more expensive and labor intensive.

Another OSU study looked at companion planting as an attempt to control squash bugs. The herbs feverfew and white yarrow were grown with the squash, and no benefit was found after 3 years.

There are other ways to help with the insect control such as planting more resistant varieties. Butternut, Royal Acorn and Sweet Cheese have shown some resistance. Also, if you have only a few plants, hand removal of bugs and eggs is effective. The eggs are diamond shaped, yellowish to bronze and are easily seen in clusters on the underside of leaves.

Another control strategy for some gardeners is to place small boards next to the vines. Adult bugs will hide under these at night where they may be found during the day and destroyed.

Other cultural controls include cleaning up all insect-containing debris from the garden at the end of the growing season. Tilling the garden in the fall will also help by exposing overwintering insects to the cold in winter. Some gardeners also find it helpful to plant a second squash crop in mid-summer, after the major insect activity in spring and early summer has passed.

Lastly, organic and conventional insecticides are available for help with control. You may find these listed online by searching for squash bugs at the Oklahoma State Horticulture website.

Garden tips

Lace bugs, aphids, spider mites, bagworms, etc. can start popping up in the landscape and garden later this month. Keep a close eye on all plants and use mechanical, cultural, and biological control options before going to insecticides. If an insecticide is needed, use one of the organic ones such as horticultural soap, Neem oil or pyrethrin.

Remove any winter-damaged branches or plants that have not begun to grow. Prune spring-flowering plants as soon as they are finished blooming.

Proper watering of newly planted trees and shrubs often means the difference between success and replacement.

Plants Poisonous To Dogs

Some plants are harmful to pets

Bill Sevier: Ask a Master Gardener

Saturday, April 16, 2016

Q: Are there some plants I should not plant in an area where my new dog will be? T.M. Jenks

A: Dogs, especially young dogs, will taste and chew anything within reach, including indoor and outdoor plants. If the taste is not too bad, they will eat plant parts and in some cases become very ill. Poisonous plant ingestion is one of the leading causes of emergency visits to veterinary facilities.

Many plants are poisonous to dogs, and the ASPCA has an inclusive list of more than 400 plants to avoid. The Humane Society has a more practical list of about 100 indoor and outdoor plants. These lists apply to dogs and to cats, as well, to a certain extent. Cats have their own list of plants to avoid, and there is not a complete overlap of plants poisonous to both.

When a plant is listed as “poisonous” to a dog, it doesn’t mean that it is lethal. Some of these plants do have some serious toxins, such as chemicals in the glycoside family, which may cause toxicity to the heart and severe kidney damage. These may certainly be lethal. But the majority of plant toxicity is survivable for pets and is often limited to gastrointestinal and mild systemic symptoms. Fortunately, many of the toxic plants either irritate a pet’s mouth or have undesirable tastes, which limits their intake.

In any case, if your pet is sick and you suspect it has eaten some plant parts, they should be seen as soon as possible by your veterinarian.

The UC Davis Veterinary Teaching Hospital lists the following 12 plants, mostly indoor plants, responsible for the majority of their emergency calls. They are lilies, lily of the valley, anemone, aloe vera, amaryllis, asparagus fern, daffodils, philodendrons, jade plants, chrysanthemums, cyclamen and sago palms.

Out of the 100 plants listed by the Humane Society as having potential toxicity, most are ornamental perennials. Some of the more common ones are autumn crocus, azalea leaves, black locust pods, horse chestnut (buckeye), buttercups, caladium, castor bean, chinaberry berries, common privet leaves and berries, larkspur, dieffenbachia (dumb cane), Dutchman’s breeches, Easter lily, elderberry, elephant’s ear, English ivy, bittersweet vine, foxglove, holly berries, hyacinth, iris, lantana, laurels, mistletoe, morning glory, narcissus, Irish potato leaves, rhododendron, rhubarb leaves, star of Bethlehem, wisteria, yellow jessamine and yews.

If you are getting a new dog or if you have one and are considering a new plant, either indoors or out, it would be worth your time to go to the Humane Society’s website and review its list of plants. It has not only the names of the plants listed, but also the parts of plants that are considered to be toxic.

Garden tips

§  Don’t spray insecticides during fruit tree bloom or pollination may be affected. Disease sprays can continue according to schedule and label directions.

§  Mowing of warm-season lawns can begin now. Cutting height for bermudagrass and zoysia grass should be 1 to 1½ inches high, and buffalograss 1½ to 3 inches high.

§  Harden off transplants outside in partial protection from sun and wind prior to planting.

§  Hummingbirds arrive in Oklahoma in early April. Get your bird feeders ready using 1 part sugar to 4 parts water. Do not use red food coloring.

Controlling Moss in Lawns

Moss is red flag for poor lawn conditions

Bill Sevier: Ask a Master Gardener   

Saturday, April 9, 2016  

Q: In a shady part of my lawn, there is moss growing in some bare spots. Is there something I can spray to get rid of it? Alan, Tulsa

A: There are sprays to kill moss, however, to not address the underlying problem is the wrong approach.

Moss, like an invasion of undesirable weeds, is usually a red flag that something is wrong with your turfgrass growing conditions. Situations favoring moss growth are too much shade, poor fertility, excessive moisture, soil compaction and overly acidic soil. The best solution is to identify and correct the problems; if not, moss will only return.

To correct deficiencies, start off with a soil test. This will measure soil pH (acidity) and the nutrients nitrogen, phosphorus and potassium.

The pH needed for most lawn grasses is slightly acidic — between 6 and 7. Most turfgrass in Oklahoma will grow but perform less well in more acidic soils. Moss prefers just the opposite, growing better in more acidic soils. To correct an overly low pH, add dolomite lime. This adds alkali and raises the pH to more favorable levels. Instructions about using lime may be found in OSU fact sheet 6007, “Improving Garden Soil Fertility,” at tulsamastergardeners.org.

Many mossy lawn patches are compacted, often related to foot or vehicular traffic. To reduce compaction, till 3 to 4 inches of organic compost into the soil. This will not only improve drainage and air movement, but will also add fertility. Do not use peat moss as your organic compost; peat moss is too acidic and may make the situation worse.

The soil test will indicate which nutrients may be needed. Add only those suggested by the test results. Do not add nutrients such as phosphorus unless proven to be deficient. Adding more to soils with pre-existing high levels will not only harm plants, but also can result in pollution.

Areas that are too shady may be difficult to deal with unless trees can be pruned to allow more light. Likewise, overly wet soils will need some attention to drainage depending on the situation.

Several commercial products are labeled for moss control. These contain either a type of soap, bleach or various mineral salts of copper. They all seem to be somewhat effective. However, many of these preparations may also damage other plants, so the label must be read and followed carefully.

After eliminating moss, shady areas can be planted with tall fescue turf grass, or if too shady for fescue, plant a shade-tolerant ground cover. OSU has an excellent fact sheet, “Managing Turfgrass in the Shade in Oklahoma,” available online.

Be aware that growing moss is not considered undesirable by everyone. Some people go to great extremes creating “moss gardens” as a place of peace and serenity. Several books have been written about how to create these gardens. This fact demonstrates clearly the adage that “beauty is in the eye of the beholder.”

For more information or to ask a question about gardening, contact the Master Gardeners at 918-746-3701 from 9 a.m.-4 p.m.

Garden tips

§  March is the second best time of the year to seed cool-season turfgrasses — tall fescue and Kentucky bluegrass; however, fall is far and away the best time to plant them.

§  Prune roses as needed now and begin a regular spray program on varieties susceptible to black spot disease.

§  Early to mid-April is the time to plant most warm-season vegetables such as Lima and green beans, cucumber, pumpkin, summer squash, tomatoes, eggplant, pepper and okra. Complete listings for when to plant cold-season and warm-season vegetables may be found online. It is titled “Oklahoma Garden Planning Guide,” #6004 and may also be found on the Master Gardener website.

Slender Trees for Smaller Areas

Slender trees work well for smaller landscapes

Brian Jervis: Ask a Master Gardener

Saturday, April 2, 2016

Q: My house and my neighbor’s are only 14 feet apart. I would like to have a tree in that space, but it would have to be slender. Do you have suggestions? M. A., Tulsa

A: Many urban homes have small lawn areas between houses and street-side. A standard 60-foot-tall oak that might have a 60-foot-spread is not a consideration. To accommodate smaller landscapes for those wishing to plant a tree, slender versions may be more attractive and useful. They may be planted in rows for a more formal setting to define boundaries and as a screen for sight and sound. One loses the shade benefit but may be compensated by the slenderness asset.

These trees are often referred to as “columnar” or “fastigiated” forms. As demand for these trees has increased, more and more slender forms of familiar trees have entered the market to become available. Many of these trees are needled evergreens, but there are deciduous cultivars and even fruit trees.

A good place to go to see some of the varieties of columnar trees is the Monrovia website. There are photos and information about growing conditions for more than 100 varieties.

A few of the trees that might be of interest to a Tulsa-area homeowner are listed below.

A slender version of eastern red cedar, the Taylor juniper is an excellent choice. Junipers, not cedars, love Oklahoma and will grow up to 30 feet tall and 3 feet wide. No pruning needed, ever. This tree comes close to an ideal replacement for the Italian Cypress grown commonly in the Mediterranean region. Italian cypress will grow in Oklahoma but may not survive an unusually cold winter.

Another tree that is an increasing favorite of landscapers is a slender form of the southern magnolia. “Little Gem Magnolia” grows to 20 feet tall and up to 10 feet wide. A smaller cultivar, a dwarf of Little Gem, grows only to 10 feet. These trees are evergreen, have nice shiny leaves and huge beautiful blossoms in spring.

Another great tree to consider is the regal English oak, “Fastigiata.” These may grow to 50-60 feet and up to 15 feet wide. This European import is elegant and grows well in our area.

The accompanying photograph is of a columnar sweetgum tree with fall foliage in the North Carolina Botanical Garden. It is an extreme example of a slender cultivar of a common tree.

There are other slender versions of trees to choose from. Cultivars of the sugar maple, European hornbeam, hollies, arborvitae, cedars, bald and other cypresses, tulip tree, cherry, hawthorn and many junipers are marketed.

Local nurseries have a fairly wide selection to choose from. If you want a tree not available locally, the nursery may order it for you, or you can get a smaller plant by mail and grow it in a pot for a couple of years before planting permanently.

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For more information or to ask a question about gardening, contact the Master Gardeners at 918-746-3701 from 9 a.m.-4 p.m.

Garden tips

§  Most bedding plants, summer flowering bulbs and annual flower seeds can be planted after danger of frost. This happens around mid-April in most of Oklahoma. Hold off mulching these crops until soil temperatures warm up. Warm-season annuals should not be planted until soil temperatures are in the low 60s.

§  The soil temperature for our area as of Wednesday was about 59 degrees. Soil temperatures may be found on the Oklahoma Mesonet website.

§  Harden off transplants outside in partial protection from sun and wind prior to planting.

§  Don’t plant tomato sprouts too early. The soil temperature is key and should be above 60 degrees before planting. If the soil is too cool, the plants will sit there and not grow. Remove the blossoms from any tomato plant at the time of planting, it needs roots before making tomatoes.