Crape Myrtle Bark Scale

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Spring has officially sprung, and the wildflowers are outstanding this year! I have really enjoyed watching the wildflowers change from Bluebonnets to Primrose to Indian Blanket, and I cannot wait to see what comes next.

Springtime also brings a lot of insects. One insect that I have written about before, Crape Myrtle Bark Scale (CMBS), is showing up this spring on Crape Myrtles and some new plant hosts.  CMBS is a small, white, sap-feeding insect that lives on the bark of crape myrtle trees.  The adult females look like tiny pieces of popcorn attached near pruning wounds or in the branch crotches.  They are usually 2mm in length.  If you squish the scale, it has bright pink insides.  CMBS does not kill the tree, but it can cause reduced flowering and the scale secretes a honeydew that causes sooty mold.

The AgriLife Extension Specialists in College Station are doing good research on CMBS, and they recently presented information about other plants that have become hosts to this scale insect. Boxwood, pomegranate, cleyera, hackberry, persimmon, soybean, figs, Ligustrum, apple, and beautyberry have all been confirmed as hosts for Crape Myrtle Bark Scale.  This week, I had two Williamson County Master Gardener Volunteers bring a sample of their beautyberry with CMBS.

The good news about CMBS is that we have several treatment options, and now is the time to do it! If you just spot a few, you can squish them.  You can also use soapy water and a brush to remove infestations from your plants.  Scrubbing your tree can also help remove sooty mold.  Ladybeetles are a natural enemy of CMBS, if you prefer to use a biological control option.  If you have a heavy infestation, AgriLife Specialists recommend a systemic insecticide application to be made in March – May.  Imidacloprid and dinotefuran are two systemic insecticides that you can apply as a soil drench.  Both chemicals have been shown to be highly effective at managing scale populations when they are applied in early spring.

Irrigation Audit

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As the weather warms up this spring, it’s time to start thinking about lawn care again. Right now is a great time to check your lawn irrigation system to make sure everything is ready to go for the summer watering season. An irrigation audit is a great way to make sure your system is operating efficiently so you can conserve water in your landscape.
An irrigation audit consists of three parts: site inspection, performance testing, and irrigation scheduling. A site inspection is an easy step. Turn on your irrigation system to make sure all sprinkler heads pop up; check the spray pattern to ensure water is not spraying onto streets, sidewalks, and hardscapes; and check for any broken or missing sprinkler heads from mower damage. All of these problems are great DIY projects.

Performance testing is a way to check how much water your irrigation system is putting out in your lawn. The best way to check this is by setting out some mini rain gauges. I often use tuna cans or small plastic food storage containers. Put the cans out in several spots throughout the lawn, run your irrigation system for ten minutes, then measure how much water was fallen in each can. This helps you know the average amount of water your system puts out in ten minutes, and you can adjust your schedule to get the appropriate amount of water on your lawn each time you water.

Irrigation scheduling is the final, and possibly most important step in an irrigation audit. There are a lot of factors that go into the formula for figuring out how much water a lawn needs (temperature, relative humidity, plant requirements, soil type, etc), but the rule of thumb for turfgrass is one-inch per week in the summer and less in the spring and fall. You can divide your watering schedule into two times per week at half an inch per irrigation time. The most important thing to remember is to only water if your lawn needs to be watered. Look for visible wilt in your turfgrass. Do not irrigate after a good rain.

Texas A&M AgriLife Extension has a program called “Water University” with great video tutorials and fact sheets about fixing irrigation systems, cycle soak irrigation, and water conservation. Check it out at https://wateruniversity.tamu.edu/. Contact your city’s water department to find out when you are allowed to water your lawn and if they offer a rebate program for conducting an irrigation audit.

Large Patch in Turfgrass

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Spring is in the air! I love seeing the trees bud out and the lawns green up, and I’m enjoying the nice weather.  Unfortunately, this beautiful spring weather has created perfect conditions for large patch in our St. Augustine grass and zoysia grass.

Rhizoctonia solani is a fungus that is present in the soil year-round, but it takes advantage of cool temperatures and wet soil to cause a turfgrass disease known as large patch (sometimes referred to as brown patch in cool-season grasses.  The first symptom of large patch is circular, discolored patches in the turf.  An easy way to diagnose large patch is to pull on the grass blade or shoot.  A diseased shoot will pull out very easily and will have a dark brown lesion that looks a little rotten.

I have good news and bad news about large patch in the spring. The good news is that grass will recover from light disease symptoms as the temperatures rise in the late spring, and new growth should fill in during the summer.  In fact, Texas A&M AgriLife turf specialists say that treatment is not cost-effective in the spring because the warm temperatures will take care of the disease for now.  If there was extensive crown and root damage, however, you might need to put down new sod in the damaged areas.  The bad news is that large patch is hard to get rid of and will probably come back in the fall.  You need to be prepared to treat with a fungicide in the early fall to control large patch.

Large patch thrives in lawns that have poor drainage and are over-fertilized. Good lawn management can help avoid outbreaks of large patch.  A few tips for lawn management:

  1. Improve drainage in your lawn, and only water when necessary.
  2. Mow regularly at appropriate heights. St. Augustine should be mowed at 2-3 inches, and zoysia should be mowed at 1-2 inches.
  3. Do not over-fertilize. Fertilize three weeks after spring green-up. Our grass is just starting to really green-up, so wait until the end of April to fertilize.

Aphids

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Aphids are a hot topic of conversation at the AgriLife Extension Office this week! First, we spotted aphids in the vegetable garden!  Then several homeowners called with questions about their crape myrtles with black limbs, which is usually caused by sooty mold that colonizes on aphid “honeydew.”  Aphids are on the move and they are an interesting pest!

Aphids are small, soft-bodied insects that range from 1/16 to 1/8 inch. They vary in color from black, gray, red, orange, green, yellow, blue-green, or white, depending on the species and the plants they feed on.  Most aphids don’t have wings, but there are some species that develop wings in response to environmental conditions.  Aphids have long slender mouthparts that they use to pierce stems, leaves, and other tender plant parts and suck out fluids.

Reproduction of aphids happens very quickly. Many aphids can reproduce asexually, and adult females can give birth to live offspring, instead of laying eggs.  Some species can give birth to as many as 12 live young each day. Other species mate and produce eggs in fall or winter, and the eggs overwinter on the foliage of perennial plants.  Many aphid species can develop from a newborn nymph to mature, reproducing adult in seven to eight days.  It’s no wonder that aphids can reproduce faster than any other insect!

Damage from aphids can be extensive. Low numbers of aphids are not usually a problem in a garden or on trees, but a large population of aphids will damage leaves and stunt shoots.  Aphids also secrete a sticky substance called honeydew that falls on leaves, trunks, and anything below the plant.  If you’ve ever stood underneath a pecan tree on a cloudless day and felt “rain” you probably received some honeydew.  Honeydew can be a problem because a fungus called sooty mold (Capnodium spp.) colonizes on surfaces coated in honeydew.  Sooty mold keeps sunlight from reaching the leaves of a plant, preventing photosynthesis.  Sooty mold is the culprit behind the black limbs on crape myrtles.

The best way to manage aphids is to closely monitor your plants once or twice each week, especially in the spring and fall. Aphids can usually be found on the underside of leaves or on new growth.  You can remove a lot of aphids with a strong stream of water from a water hose or by knocking them off.  Lady beetles and lacewings are both good predators of aphids and provide some natural, biological control of aphids.  Insecticidal soaps or oils are another effective control measure, and you can find many insecticides that are effective against aphids.  If you spray insecticides in a fruit or vegetable garden, check the label to make sure the insecticide is approved for food crops.

Tomato Varieties

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It only seems right that March should usher in springtime weather, but this year it brought a strong cold front through Central Texas. Of course, the cold front came just in time to endanger the young tomato transplants that we passed out at a recent Tomato Lunch and Learn at the AgriLife Extension Office.

Despite the cold, I am very excited to see how the tomatoes perform. This year we are trying out two new varieties at the Demonstration Garden, Celebration and Super Sweet 100.  Two very dedicated Master Gardeners volunteered to grow more than 100 plants of these two varieties from seed.  The seeds were planted in January with a 98% germination rate, and they grew really fast with the help of a greenhouse, some grow lights, and the tender care of the Master Gardeners.

Celebration is a hybrid determinate tomato. It is an improved Celebrity variety that is crack, drought, and disease resistant.  This is a compact plant that should mature early with 8-ounce tomatoes.  If you have grown Celebrity tomatoes, you might want to give Celebration a try this year.  Or you can come check out the demonstration garden and make your decision based on how it does for the Master Gardeners.

The other variety that we are trying this year is Super Sweet 100. This is an indeterminate hybrid variety that matures in 65 days.  The plant produces small 1-inch tomatoes that are super sweet and very nutritious.  The claim to fame is that they contain more vitamin C than any other tomato.

You can find recommendations for the best varieties for Williamson County on the Aggie Horticulture website at https://aggie-horticulture.tamu.edu/.  The vegetable variety selector allows you to choose from a wide variety of vegetables.  This is a great place to start if you are new to Williamson County or new to gardening.  We are always trying out new varieties at the Demonstration Garden at 3151 SE Inner Loop in Georgetown.  The Master Gardeners work in the garden on Tuesday and Friday mornings if you have questions about gardening or want to see what we are doing.

Hopefully the cold weather is finished, and we can start planting our tomatoes in the garden. Remember that tomatoes are susceptible to frost so you need to wait until the danger of frost is passed or cover your tomato plants to protect them.

Crape Murder

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It is almost spring in Texas, and the gardeners are getting busy! A few weeks ago, I shared information about pruning to help train plants, remove dead or diseased branches, and improve the quality of flowers and foliage.  As I drive around Williamson County, I have noticed that the crape myrtles in some landscapes are pruned a little too much.  In fact, we call this kind of pruning Crape Murder!

Crape myrtles are a beautiful flowering plant that can be grown as a shrub or shaped into a tree. Crape myrtles are low maintenance and add color to the landscape in the summer with beautiful blooms, in the fall with colorful foliage, and in the winter with interesting bark.  Unfortunately, many homeowners and landscapers have a terrible habit of severely pruning or “topping” crape myrtles.  This type of pruning is not necessary for crape myrtles to bloom.  Topping crape myrtles delays their blooms, creates weak limbs where the new growth comes out, and makes ugly knobby scars where the prune cut was made.

There are a few times when pruning a crape myrtle is appropriate. You can prune the suckers that grow from the base to help shape the crape myrtle.  Prune the suckers at ground level.  You can also prune if branches are crossed and rubbing or are touching a structure or roof.  Those are the only situations when it is necessary to prune a crape myrtle.

Sometimes, crape myrtles are topped to limit the growth because they get too tall. Stop it!  Crape myrtles come in a variety of sizes from three feet tall to 35 feet tall. If your crape myrtle is too tall for your lawn, remove it and plant a new one that will grow to the appropriate size.

Please stop the crape murder this year! Texas A&M AgriLife Extension has a great FAQ and video about how to prune a crape myrtle.  You can check it out on our Facebook page by searching for Williamson County Agriculture – Texas A&M AgriLife Extension.  For more information about caring for crape myrtles, contact Kate Whitney, Williamson County Horticulture Extension Agent, at 512-943-3300 or klwhitney@ag.tamu.edu.

Summer Weed Pre-emergent

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It’s officially winter in Texas! Warm one day and cold the next!  This time of year is challenging for gardeners because we worry about protecting plants from freezes, getting enough chill hours for our fruit trees, and trying to control winter weeds like henbit, dandelion, and wild carrot.  Unfortunately, it’s also time to think about preventing our warm season weeds like crabgrass, carpetweed, pigweed, and many others.

Mid-February is the time to put out pre-emergent weed killers if you have problems with weeds in your lawn. A pre-emergent herbicide will kill weeds before they begin actively growing.  You need to consider two important factors when you prepare to treat weeds.  What kinds of weeds do you have and when is the best time to treat them?

Broadleaf weeds have netted leaf veins in a variety of leaf shapes. An example of a broadleaf weed is henbit or ragweed.  We have a wide range of herbicides that will target just broadleaf plants.  A good pre-emergent herbicide for broadleaf weeds is isoxaben, commonly found in products like Gallery or Fertilome Broadleaf Control with Gallery.  This is a granular product that should be broadcast using a spreader and watered into the lawn.

Grassy weeds have parallel veins with long, slender leaf blades. Crabgrass and sandbur stickers are common grassy weeds.  You need a separate herbicide that will target grassy weeds.  Some good options for grassy-weed pre-emergents are prodiamine found in Barricade; pendimethalin found in Scott’s Halts Crabgrass Preventer, Pre-M and many others; or dithiopyr found in Bonide Crabgrass preventer.  These are also granular products that should be made in a separate application than your broadleaf herbicide.  Just think of how many extra steps you can get in while you work!  Gardening is a great fitness program.

Be sure to put out pre-emergent herbicides by mid-February. They don’t work if the weeds have already germinated and started growing.  Timing is very important.

One final note, many people like to double up on tasks and use a “weed and feed” product to treat weeds and fertilize the lawn at the same time. This sounds like a time-saving step, but we need to treat weeds now and it is much too early to fertilize.  Any fertilizer you put out now will be used by the winter weeds that are growing or will be wasted.  Wait until mid-April to fertilize when the grass is actively growing and needs nutrients.

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Planting Trees

 

Earlier this week, the Williamson County Master Gardeners and I got to visit a third-generation nursery in De Leon, Texas, that grows and sells many of the pecan and fruit trees that are grown throughout Texas. Winter is a great time of year to plant pecan and fruit trees, so the staff at the nursery were running to fill orders.

If you are thinking about planting trees this month, you need to know some important things about properly planting your tree. You can do everything right in caring for your tree, but improper planting will set you up for heartache.

Pick a site in full sun with enough space for the tree to grow. Check to see how high your tree is expected to grow.  Will it reach nearby powerlines or buildings?  Does it have enough room for the roots to grow?  The roots can extend past the tree canopy, so find plenty of space for the tree to grow up and out.

Trees are sold in containers or as bare-root stock. Dig your hole to be twice as wide as the container or root ball, but only dig it as deep as the container.  You need to be very careful that your tree is not planted too deep or too shallow.  The point where the top-most root emerges from the trunk needs to be within two inches of the soil surface.  Roots require oxygen to grow, and they cannot get oxygen if there is too much soil over the roots.  If your tree comes in a container with soil, you might need to dig down into the pot a little to find the top roots, so you know how deep to plant.  If the roots are growing in a circle in the pot, cut the roots and spread them out.  If you don’t cut circling roots, they will continue to grow in a circle instead of spreading out into the soil.

After you put your tree into the hole, use the original soil to fill the hole back. It’s tempting to add compost, potting soil, or peat moss to give the tree a boost, but do not even think about it!  The tree roots need to expand into the soil and grow out, and they will not do that if you create a “pot” for them in the ground with compost or potting soil.  Be sure to water thoroughly to help the soil settle and remove air pockets.  Add mulch around the tree to help keep the soil moist and regulate soil temperature.

Mark your calendar for Tuesday, February 5, for a workshop on planting and pruning fruit and pecan trees. Dr. Larry Stein, Texas A&M AgriLife Extension Horticulture Specialist, will give a workshop with hands-on activities.  Register online at https://williamson.agrilife.org/program-registration/.

Pruning

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If there is one time of year that gardeners should earn a rest, you might think winter would be it. Gardening does slow down in the winter, but a gardener’s task list is never completed. Pruning is a great winter task that I look forward to because it means spring growth is just around the corner!

Pruning is used to train plants, maintain plant health, improve quality of flowers, fruit or foliage, and to restrict growth. Advances in plant breeding and selection have provided a wide range of plants that require very little, if any, pruning, but there are some plants that need a good trim.

The best time to prune many plants is late winter and early spring. We want to prune at a time when there will be the least amount of damage to the plant. Plan to prune before plants put on new growth in the spring. In the spring, plants put considerable energy into developing new growth. If you wait too long and prune off that new growth, the plant has used up a lot of its resources and doesn’t have the new growth available for photosynthesis.

Plan your cuts by following a plan. First, remove all dead, broken, diseased, or problem limbs. Cut them at the point of origin or back to a strong lateral branch or shoot. Second, you can make any training cuts that are necessary. Lateral branches are branches that originate from the main trunk. You can prune lateral branches to help train your plant to a desired shape. Be sure to know the natural growth habit of your plant so you can prune for a natural look (i.e. shrubs are not naturally square). Finally, make any corrective pruning cuts to eliminate narrow crotches, double leaders, or water sprouts. It’s helpful to take a step back and check your work.

Many people call me to ask about pruning paint or wound dressing. Research has found that wound dressing is not necessary and might slow down the healing process. The only exception to this rule is for oak trees. We have oak wilt in Williamson County, so you need to take care to paint all pruning cuts with a latex paint within 15 minutes of the cut to prevent the spread of the disease.

Texas A&M AgriLife Extension has great instructions for pruning specific types of plants at https://aggie-horticulture.tamu.edu/earthkind/landscape/proper-pruning-techniques/.

Lettuce Variety Trial

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This fall we had an excellent crop of lettuce in the Demonstration Garden at the Extension Office!  In October, the Master Gardener Volunteers and I planted a lettuce trial to find out which varieties of lettuce grow well in Williamson County.  We chose ten varieties that are sold in local nurseries and farm stores including Black Seeded Simpson, Nevada, Buttercrunch, Prizehead, Giant Caesar, Crawford, Red Salad Bowl, Igloo, Burpee Bibb, and Limestone.

October 17, 2018

Following the recommendations for planting lettuce, we prepared our garden beds with compost worked into the soil.  Lettuce is a very small seed that needs to be planted at a depth of 1/8 to 1/4 of an inch in rows that are 12 inches apart.  We just used our fingers to lightly draw a line down the row and sprinkled in the lettuce seed.  We covered the seed with a light layer of soil and watered by hand to keep the soil moist.

October 30, 2018

Lettuce is a fun crop because it’s easy to plant and germinates quickly.  Most of our lettuce germinated within a few days.  You can thin the crop to about 8 inches between lettuce plants if you want to grow full-sized heads of lettuce.  We decided to harvest the lettuce when it was young to have “baby greens” like you often see in the stores, so it was not necessary to thin the lettuce.  Lettuce should be fertilized three weeks after planting, and nitrogen is important for lettuce to grow and produce a high-quality, dark green product.

November 19, 2018

Lettuce is harvested by cutting it at the base of the plant to get a full head of lettuce.  You can also trim the outer leaves and leave the center leaves to continue growing.  Lettuce gets bitter as it matures, so it’s best to pick it when it is young.  Lettuce keeps in the refrigerator for up to 10 days in a loose plastic bag.  Be sure to wash it well.

December 5, 2018

You can plant lettuce in the fall through early spring.  Lettuce can handle a light frost, and you can use a row cover to protect it from a harder freeze.  Lettuce does not do well when temperatures get about 80 degrees Fahrenheit.

Lettuce has some great health benefits.  It is naturally low in calories and sodium, with about seven calories per cup.  Lettuce contains Vitamin A, Vitamin C, beta-carotene, calcium, folate, fiber, and phytonutrients.  Plus, lettuce is usually eaten with other fruits and vegetables in a salad or wrap, so you get the added benefit of extra nutrients.

We had a great lettuce harvest from our trial, and we continue to harvest!  All the varieties did well, except for Nevada and Crawford.  Our trial had poor germination rates for those two varieties, but the few that did germinate were very tasty.  I am a little bit of a stubborn gardener, so we just might have to try again with those varieties!

Please stop by to see the lettuce trial at our Demonstration Garden at 3151 SE Inner Loop, Georgetown, or call Kate Whitney, Horticulture Extension Agent, for more information at 512-943-3300.  Be on the lookout for our next variety trial!