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July 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:
Mr. Rodriguez, in considering Asiatic Jasmine as a ground cover, I found a listing on the web (only one) that mentioned that parts of the plants are poisonous. Is this true? Are they poisonous enough to be an issue in an area where small dogs would have access (and a puppy might chew)?
Answer:
Mrs. Jackson, I find nothing to indicate that this plant is toxic. It is certainly one of the most used ground covers in Texas. The deer eat it and suffer no ill effects that I have seen.

Question:
Dave, what is the best way to control stink bugs in the vegetable garden?
Answer:
Steve, I have had the best luck with one of the insecticidal dusts such as Thiodan, Sevin or Permethrin. Some people say that liquid Spinosad has had some results.

Question:
Mr. Rodriguez, we are losing leaves off of our live oak (past the time they normally fall) and all of them have orange powdery spots on the underneath. Can you tell us what it is and what we can do?
Answer:
Charlie, I cannot tell you what fungal disease the tree has. It could be rust. Regardless, I do not think that there is anything to worry about. We have had a banner spring for fungal diseases but fortunately most of them are not life threatening. The tree should quickly replace the leaves it is losing. Consider contacting a certified Arborist if it becomes to detrimental for the vigor of the tree.

Question:
Mr. Rodriguez, what type plants/flowers can a person plant to repel mosquitoes, gnats, wasps, etc?
Answer:
Howard, there are no plants that will effectively repel insects. There is a scented geranium sold as Citronella Plant that might repel mosquitoes for a distance of a few inches but not enough to be of assistance.

Question:
David, will cross pollination occur if I have a neighbor plant a pear tree and also should it be the same type of pear tree or a different pear tree? They will be about 500-600ft apart.
Answer:
The pear is self non-fruitful and usually will not set a good crop of fruit with its own pollen. Therefore, at least two different varieties must be planted near each other for cross-pollination. Insects, especially honeybees, carry pollen from one tree to another. Unfortunately, pear flowers produce little nectar and are less attractive to bees than many other types of flowers. Therefore, it is important to plant pear trees close together, preferably within 70 feet of each other for cross-pollination.

Question:
Mr. Rodriguez, what can grow under an oak tree that is totally shaded all day? It is a spot between our house and the tree and nothing seems to grow there.
Answer:
Robert, nothing grows under the oak tree because it is getting most of the moisture. When given sufficient water you can grow such shade loving plants as Asian Jasmine, English Ivy, Turk's Cap, Mondo Grass, and possibly Liriope.

Question:
David, can I spray any type of weed killer on Asian Jasmine that was planted in early April.
Answer:
Fred, once Asian Jasmine is hardened off, you can spray it with just about any herbicide without damaging it. Since it is newly planted and actively growing, I would be careful of over spraying it with anything. If the plants are small and separated, you could protect them by covering them with anything (such as buckets, cardboard boxes, milk jugs, etc.) that would prevent the herbicide from getting on the plants and spraying the weeds I recommend that you use a glyphosate (i.e. Greenlight Complete) product but at a reduced strength (perhaps ½ of recommended).

Question:
Mr. Rodriguez, I planted shrimp plants last year and they did great. This year they are bigger but the leaves are a light green color. The leaves look 'munched on' and they have no blooms. The other plants are doing well. What can I do to make these plants healthy again?
Answer:
Steven, if the shrimp plants froze to the ground (or you cut them back), the plants haven't had time to bloom. The light green leaves indicate that they might appreciate fertilizer. Any good high nitrogen (first number) slow-release fertilizer such as 19-5-9 will be fine. Spread about a cup over the area of the bed and water in. The 'munched on' look, in most neighborhoods this year, is caused by snails which have been out in abundance. Any of the Bug and Snail baits that all nurseries/garden centers carry will control them.

Question:
David, we have a live oak tree in our yard that has a hole in the trunk. What should I do to cover this open hole or should I do anything? I was told not to use concrete, but I'm concerned about leaving the opening. The hole is about four inches round.
Answer:
Jake, the current thinking by the experts is to do nothing. The wood in the hole will heal itself quicker without help or hindrance from us.

Question:
Mr. Rodriguez, we have about 15 Crape Myrtle trees. We noticed the leaves are cupping, and some of the lateral branches have a problem. The exterior bark is soft and able to be peeled off on some of the lateral branches. Certain areas of the lateral branches that are affected are also a lightly different color.
Answer:
Franklin, check your crape myrtles for aphids. If they are aphids, the upper surface of the leaves should be sticky with honeydew. Any insecticide will take care of aphids. The crape myrtles exfoliate (shed) their bark each year. This is a natural feature of the crape myrtle and enhances its beauty.

Question:
David, this is my first time growing cucumbers. We watched patiently as our plants grew into massive "bushes." The cucumbers had many blossoms and a few small cukes (about three-to-four inches). One day, I noticed three cukes about 10 inches long and about eight inches round. The cukes were not solid green, but more green at the stem and fading to almost white. We thought, surly these are "ready" to eat. Not! Very, very bitter. What went wrong?
Answer:
Evelyn, those cukes are sneaky about hiding in the foliage of those massive bushes. Cucumbers grow very quickly and are ready for harvesting any time after they get about six inches long. You left them on the vine far too long.

Question:
Mr. Rodriguez, where can I buy horse herb?
Answer:
Nelson, Horseherb (Calyptocarpus vialis) is not readily available to purchase commercially. However, it seems to grow everywhere. I recommend that you dig some up from public property (bar ditches along side of roads) or private property (with consent of owner) and transplant it into your yard. You will then have it forever as it is a perennial that reseeds prolifically.

Question: David, will it harm my Monterrey oak to prune a lower limb in July? The limb is extending over a sidewalk. The tree is two years old and appears very healthy.
Answer:
Fred, no, it will not hurt the tree. While the Mexican White Oak/Monterrey Oak is said to be resistant to oak wilt, I would go ahead and paint all pruning cuts with any latex paint as protection.

Question:
David, my roses have a white sticky substance on their limbs. Some of it is on the leaves. It doesn't match the description of powdery mildew that I can find on the internet. Any ideas? I'm spraying it with fungicide and that seems to take care of the immediate problem. Any long term ideas?
Answer:
I think that you will find an insect in that white stuff. It is probably a small leafhopper most notable for its production of wax. This critter is not believed to cause substantial damage to most plants, apart from the messy appearance of the wax. There is no common name that I know of. Control with horticultural oil, soap, or one of the systemic insecticides, if needed.

Question:
What can I use to soften my soil for planting? When digging in my yard the soil is very sticky and adheres to my shovel. Also, I find that my soil has lots of rocks and stones.
Answer:
The incorporation of copious amount of organic matter such as compost, along with about two inches of washed masonry sand, will make your soil more friable. Much of the soil in our area is thin with many rocks and stones. For ease of working the soil again and again, you should remove as many of these as possible.