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We hope your Summer
has been good!

Moldy Black Stuff?

Most of us have seen it and some of us thought that it was just a “Houston thing.” But all of us hate it and it can even cause damage, not to plants but to homes, patios, automobiles and outdoor equipment and furniture.

It’s called Sooty Mold, and it’s not just a Houston thing but affects plants and gardens everywhere. Actually a secondary symptom of a larger problem, Sooty Mold is actually a harmless fungus that we find on the tops of leaves of Crepe Myrtle, Wax Ligustrum, Gardenias and Citrus to name a few. It also grows on hard surfaces like patio furniture, propane tanks, cars and trucks, concrete or wood or brick surfaces and anything that is underneath the primary problem – insects.

Insects like Aphids, Mealy Bugs, Leafhoppers, and Scale have piercing and sucking mouthparts. They use these to feed on sap from the leaves and stems of plants. Many times, these insects inhabit large shrubs and trees where we can’t see them. As they feed, they excrete sugary “honeydew”. The honeydew is also a food source for certain bees, ants and wasps that use the aphids like cows, “milking” the hondydew droplets. This is a great example of symbiosis, and the ants can also be a diagnostic tool for you to identify that you have another insect problem.

The honeydew not harvested by other insects drops down and sticks to anything underneath where these insects are feeding. The sugars in this honeydew provide an ideal foundation for the growth of various fungi, including Sooty Molds. Once the moisture of the honeydew has evaporated, this sugary foundation concentrates and hardens. So, now you have a hard, sticky mess with a black fungus growing in it, and it is unsightly and difficult to remove.

The solution is to identify the Sooty Mold as a sign of feeding insects, then to control those insects. Many times we can’t spray to the height where these insects are feeding, so we have to remove the Sooty Mold by spraying or washing. In the following links you’ll find more information on Sooty Mold and suggestions for its removal.

http://www.na.fs.fed.us/spfo/pubs/howtos/ht_sooty/ht_sooty.htm

http://ohioline.osu.edu/hyg-fact/3000/pdf/3046.pdf

Yellow Leaves?

All spring, we have fielded questions and concerns over yellow and yellowing leaves on otherwise healthy plants. Why would we see this and is it a real problem?

Sometimes, yellow leaves on a plant are a natural result of its growth. As a plant grows, the mass of stems and leaves begins to shade the lower portions. This shade will cause leaves, previously accustomed to much more sunlight, to yellow and fall off. Sometimes we forget just how fast our plants grow and overlook this natural trait.

Some evergreen plants begin to exhibit yellow leaves as their new growth emerges, causing all sorts of panic and misunderstanding. Many of you have written and noticed the seasonal leaf drop on Live Oaks, Gardenias, Azaleas, Magnolias and many other evergreens in coastal Texas. And many of you have come to know that this is natural, even though the plants can appear to be on their last legs. Please, write or call us if you worry that your evergreens are dying. Chances are that they are just fine and you can avoid spending money unnecessarily.

Another reason that we’ve seen yellow leaves this summer is the huge swing from sopping wet in June to below average rainfall in July and August. I know that my patio plants began to drop leaves immediately after those heavy June rains. They had put on lots of new growth during the rain. Once the weather dried out, the root systems could not support all of that new growth. I recommend that if you experienced this, just leave the plants alone and let the root system catch up.

Of course, yellow leaves CAN be the result of a problem, and when you suspect this just remember that our Information Centers can help with identification of the disease or problem and provide you with some control options.

Previous Garden Notes Newsletters

Plants for Sun and Heat

Recently we’ve received inquiries regarding hardy, heat and sun tolerant plants. Earlier this month, Patsy asked:

“We have two urns at our front door that get the hot west sun in the afternoons. Please advise what type plant will survive the grueling heat.”

This is a very typical question this time of year. It’s too early to plant Fall plants if they were available, and too late for those spring blooming plants. There are loads of great, colorful summer plants for landscape beds or containers. Here are a few suggestions:

Hibiscus – both tropical Chinese Hibiscus and the perennial Mallow-types

Lantana – trailing and bush forms, now dwarf varieties are available

Purslane – large-flowering types are most showy and popular

Portulaca – good-old Moss Rose, ‘Margarita’ is a great new series.

Zinnia – ‘Magellan’ is the new, great series with more colors

Perennial Grasses – lots to choose from, some with blooms like Fountain Grass, others whose leaves add motion to gardens

Pentas – always beautiful in a garden or container

Celosia – both Cockscomb and the Feather types, really HOT now

Rudbeckia – perennial and traditional “Black-Eyed Susan” flowers, more varieties now available

Coleus – THE big sun garden plant for colorful foliage and extra textures

Hamelia – attracts hummingbirds and loves the heat and sun

Copper Plants – large, background plants with large, copper-colored leaves

Ixora – clusters of colorful flowers in red-orange, pink, or white

Amaranthus – ‘Early Splendor’ and ‘Molten Fire’ still the most colorful

Esperanza – yellow bells throughout the summer and fall

Dwarf Poinciana – bright orange and yellow, exotic flowers atop fern-like leaves

Angelonia – relatively new summer tropical perennial

Torenia – great new varieties of “Summer Pansy”

Cosmos – hot colors of gold and yellow for hot weather

Scaevola – cooling blue flowers for trailing groundcover color

Plumbago – ice-blue flowers on a rambling plant

Melampodium – yellow and gold daisy-type flowers for summer beds and borders

Turnera – “Buttercup” in yellow or white

Thanks for the inquiry, Patsy.