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August Questions &Answers Compiled by David Rodriguez County Extension Agent-Horticulture Bexar County

Extension educational programs serve people of all ages regardless of socioeconomic level, race, color, sex, religion, disability, or national origin.

Special thanks to Forrest W. Appleton and volunteers of the "Master Gardener Hotline" in support of the weekly gardening questions and answers.

Question:
I have an ash colored substance on the blades of my St Augustine grass. They are located in patches about the size of a saucer in the shade of a tree. I recall having these before and it seems like it eventually killed the grass in that area.
Answer:
I suspect you have a fungus growing on organic material on the soil surface, which migrates up on the grass leaves to produce its spores. Its' commonly referred to as 'slime mold' and on turfgrass will normally appear as a gray film on the leaves. Its only damage to the grass is that it can cause yellowing because of the blockage of light to the leaves. It will normally disappear on its own without action on your part.

Question:
My 10 year old upright rosemary is dying back one branch at a time. Can't find any insects or obvious symptoms. Can it be saved or is a replacement in order?
Answer:
I suspect that the very wet, cool weather is the reason for the rosemary dying. They cannot stand constantly wet roots. I recommend that you replace it and ensure that it is planted in soil that drains very well.

Question:
My father has been growing tomatoes and this year he has been noticing that they are speckled with yellow spots. What could this be and is there something he needs to spray or do nothing at all?
Answer:
If the fruit of the speckled tomato is white under the skin where the yellow speckles are at, it's probably the result of the tomato their being sucked on by stink bugs or leaf footed bugs. These bugs are hard to control. Dusting with one of the insecticidal dusts such as Sevin, Endosulfan or Permethrin will chase them off, if not kill them.

Question:
Mr. Rodriguez, should I remove the beans from our Asiatic Jasmine or not? I have heard that by removing them it would help leaf growth.
Answer:
Fred, I have never seen beans on Asiatic Jasmine before, I don't think that it makes any difference unless you don't like the way they look. If so, remove them.

Question:
Mr. Rodriguez, my newly planted hydrangea (morning sun, afternoon shade, and good soil) has leaves that are curling up and turning brown. I can't figure out what's wrong. I water regularly, I am stumped!
Answer:
Edwin, hydrangeas have a hard time in this area and are not among the plants that we recommend. They usually do fine for a year or two and then succumb to our highly alkaline soil and the excessive heat. However, since (I assume) that yours has been planted fairly recently they may be in poorly drained soil and due to all of the rain and your regular watering are suffering from too much water causing root rot and therefore the symptoms you describe. Cut back on your watering and let them dry out, if they will.

Question:
David, we have a huge live oak tree on our property with limbs that grow down to the ground. We're having a problem controlling the wild grape vines which have taken up residence in the branches of the tree. How do we eliminate the vines without harming the gorgeous live oak?
Answer:
Jason, just cut the grape vines off at, or near, ground level and then immediately paint the cut trunks with a concentrated, undiluted herbicide containing glyphosate or triclopyr. The tops will die and the herbicide will kill the roots.

Question:
Mr. Rodriguez, I have a 10+ year old Chinkapin oak in my yard that I noticed has brown rust-like spots on both sides of the leaves. Do you know what this might be and how it can be treated?
Answer:
Sally, your tree is suffering from one of the many fungal leaf spot diseases because of all of the wet and humid weather that we have had. The good new is that these diseases seldom cause life threatening damage to the tree. It may drop many of its leaves but will replace them. If it is small enough for you to effectively spray it, you can use one of the broad spectrum fungicides containing Chlorothalonil (Daconil).

Question:
David, I have a fig ivy growing on the side of my house. It is suddenly growing vigorously and seems to be bearing fruit. Could this really be figs?
Answer: Yes those are really figs but I doubt that they are edible. As the vine ages and starts putting out horizontal branches, these branches will have the fruit.

Question:
Mr. Rodriguez, should tomato plants be topped? Mine are getting very tall and have quite a few green tomatoes. How often do I need to water them now that the rain has stopped?
Answer:
No the tomato plants should not be topped. They need those leaves to shade the fruit as well as manufacture food for the plant and fruit. You water them often enough to keep them from wilting. I cannot tell you whether that is daily, every other day or what.

Question:
I have been deadheading my petunias, but they are getting leggy and not looking good. What else can I do? I'm also new this area.
Answer:
Jennifer, cut them back severely (to maybe 6 inches), fertilize them with any good high nitrogen (first number) and they will put on new growth. However, with the heat of summer upon us, petunias are not going to thrive. They prefer the cooler weather of spring and fall.

Question:
David, I am an avid back yard vegetable gardener. Due to extreme shortage of pollinators, please tell me if and exactly how to artificially pollinate.
Answer:
Greg, this may be as simple as shaking the plant if it is one that has individual flowers containing both male and female parts such as tomatoes and peppers. If the plant has separate male and female flowers like all of the cucurbits then it is a matter of transferring pollen from the male flower (the one on the long stem) to the female flower (the one with the small fruit behind it). You can do this using something like a Q-tip or small brush or you can just break off a male flower, peel back the flower petals and brush it against the female flower. To be effective, both have to be blossoms that opened that same day.

Question:
Mr. Rodriguez, are the pods or seeds of the hyacinth bean edible? Mine is loaded with pods. At what approximate length should I harvest, if edible. If not edible, should I harvest the pods to keep control of reseeding and share the seeds?
Answer:
Lynne, every part of this plant is edible. However, being palatable to your taste buds is another question? Harvesting the young immature bean pods at about two inches is somewhat consumable. Most people enjoy this plant for its ornamental value and not its consumption.

Question:
David, we planted a live oak but need to cut the bottom branches to promote growth. What time of year do we need to do that?
Answer:
Hector, you should not cut any of the lower branches from the tree until they are at least one inch in diameter. The young tree needs as many leaves as possible to manufacture food in assisting its growth. When they get that big you can cut them at any time, but you should immediately paint the fresh wounds with tree pruning paint or any latex paint to prevent the sap beetle that spreads oak wilt from having access to those cuts within the first 15 minutes.

Question:
I recently visited a friend in Omaha, Nebraska, who had over 500 hosta plants with more than 25 varieties. I think they are striking. I understand the shade requirements and can plant them on the east side of my house. What are the varieties that might be the most successful for our area?
Answer:
Yes, hostas are beautiful. However, they and Central/South Texas do not go together. If the summer heat doesn't get them, the slugs and snails will. I do not recommend them.

Question:
Mr. Rodriguez, I have a viburnum snowball that for the last two years has never flowered. What should I do for it to flower?
Answer:
Alex, San Antonio doesn't provide the ideal growing conditions for this plant. It is too hot and dry for it. The nighttime temperatures, the alkaline soils and the water quality all play major negative roles for this plant in San Antonio. Consider, amending the soil with peat moss, and fertilize often with an acidic based fertilizer.

Question:
David, what is the best way to prune or trim oleanders? As a tree? As a bush? Either way, mine look horrible.
Answer:
John, many people are having problems with Oleanders due to a bacteria disease called Oleander Blight. This blight disease kills the plant and burns it very far back. Many people have been replacing oleanders; there is no true cure for this problem at this time. Trim the plants back hard in mid-February, and trim the plants lightly after they bloom in late summer. Most people grow them as shrubs; however, with some time and work, they may be trained as single-trunk patio plants. For more information on oleander problems go to http://www.plantanswers.com/oleander_canker.htm.

Question:
Mr. Rodriguez, why are there pockets of scorched, burned leaves on the Texas Mountain Laurels?
Answer:
Steve, it is probably a watering issue. Too much water applied on the foliage by a sprinkler could be reflecting on the foliage, thus giving a burnt appearance. If that is not the case, drainage and/or the drought, and lack of supplemental rainfall could play a role here. Take a sample in to a Certified Nursery Professional or drop a sample by our office. For more information on Texas Mountain Laurel, go to: http://www.plantanswers.com/mtn_laurel.htm.