Q. Dear Neil: You have described Oakland hollies and they sound like just what I need for privacy. How well do they tolerate rocky soils, and when should they be planted?
A. I’ll take the easy question first. Since they’re always sold in containers with all their roots intact, Oakland hollies can be planted 12 months a year. Be forewarned, however, that no matter when you plant them you need to make provisions to water them deeply by hand every two or three days from mid-spring into mid- or late fall. That means you will water them with a water hose with a water wand and bubbler (not bubbler heads on a drip irrigation line). Hollies do not wilt when they are dry. They have subtle changes in color in their leaves and before people realize it, they have waited too long.
As for the rocky soils, the more organic matter they have and the fewer rocks their roots have to encounter, the better they will do. That’s doubly critical in alkaline soils.
Just for the record, don’t overlook Nellie R. Stevens hollies if you need a tall privacy screen. They grow somewhat taller than Oakland hollies and they get there a bit more quickly. Both are excellent in sun or shade.
Q. Dear Neil: My live oaks have black stuff on their bark. It swells up after rains. Is this a fungus?
A. Probably. The gray and grayish-green growths are lichens, a symbiotic population of algae and funguses, but the black growths in your small photo are something else. Unless your trees are showing some type of distress you probably don’t need to worry. The Texas Plant Clinic at Texas A&M University could culture and identify it for you if you wished. All the details for collecting and mailing your sample as well as fees are on their website.
Q. Dear Neil: I’ve been battling annual bluegrass (Poa annua) for the past year. I applied one of the pre-emergent herbicides you recommend last spring and fall using the dates you provide for this part of Texas. I’m now seeing the bluegrass starting to return. Should I be using a post-emergent?
A. There is no postemergent control for annual bluegrass that won’t also damage your desirable permanent lawngrass. The only remedy we have is to prevent it with the early fall application of a preemergent weedkiller product. For most of Texas that timing would be between Aug. 25 and Sep. 5, but in South Texas it could extend to September 15. The spring applications you’ve seen me recommend are to prevent crabgrass and grassburs.
Back to the annual bluegrass, research and field experience have shown in recent years that the weed is showing resistance to our common consumer herbicides. As a result, control may not be as complete as we’d like. That’s probably what you’re seeing, and for that we currently don’t have a good solution to offer.
Q. Dear Neil: I see lawn care people at commercial properties scalping the turf already. I have to admit that the places look a lot better when they finish. Is it harmful to the grass to trim it back so early?
A. It’s probably common bermudagrass in that kind of setting, so my answer would be no. Facing reality, they can’t clean up all of the lawns that they care for at precisely the perfect time so they have to do it over a several-week period. When we as homeowners scalp our lawns we can be much more discriminating. It’s best to do it a couple of weeks before the average date of the last killing freeze for our locale. Scalping lets the sun’s warming rays hit the soil. As the soil warms the ground, the grass starts to green a couple of weeks earlier than unscalped turf. You don’t want that happening too soon in your own lawn.
Q. Dear Neil: For the past couple of years my potatoes have been having these lesions on their surfaces. I have switched to new beds and still have the same thing happening. It does not affect the taste of the potatoes as it’s only on the skin. I really enjoy the taste of fresh potatoes. What causes this and what can I do to stop it?
A. I just spent half an hour online. This looks like potato scab. Cornell is known for their scholarly approach to horticulture. Here is what they have on this disease for the state of New York: https://www.
Each of these fact sheets points to the fact that a group of diseases is capable of causing the various types of potato scabs and that these organisms can survive in the soil with or without potatoes for several/many years. Their advice is that you start with disease-free seed potatoes and move to an entirely new garden area. Do not share contaminated soil or equipment between the two plots. Leave this part of your garden empty of potatoes and other host plants such as beets, carrots, radishes and turnips for as long as you can, preferably several years.
Have a question you’d like Neil to consider? Mail it to him in care of this newspaper or e-mail him at mailbag@sperrygardens.com. Neil regrets that he cannot reply to questions individually.
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