Of Grass Burs, Nutgrass And Ailing Pecan Trees
Neil Sperry
DEAR NEIL: I have a grass growing all over my yard. It produces green, sometimes black stickers that get in shoelaces, cuffs and dog fur. What are they, and how can I get rid of them?
Take a sample to a Texas Certified Nursery Professional at a retail garden center for identification. Grass burs are green initially, but they turn tan/brown as they mature, not black. For the record, you would apply a pre-emergent weedkiller (Balan, Team, Dimension, etc.) two weeks before the average date of your last spring killing freeze, then again 90 days later to prevent grassburs.
However, if this turns out to be a non-grassy weed you will need to use another type of pre-emergent, specifically one called Gallery on that same time schedule. Early September pre-emergent treatments will prevent cool-season weeds, that is, the weeds that grow during late fall, winter and early spring.
DEAR NEIL: The owner of the property behind mine has trees that are severely infested with worms. He does little more than spray the trees. The worms have fallen onto my property and have ruined my own tree. I don't think it will come back. Advice?
Your photos show webworm damage. While it was widespread this spring and summer, affected trees will definitely not be killed by the damage. The best control is to prune them out when you first see them with a long-handled pole pruner. Just nip off the ends of twigs.
DEAR NEIL: What should we do with roses that are bare because of black spot?
You can prune them back by 25 to 30 percent now to encourage strong fall regrowth and bloom. It is getting late for this trimming, however, so do it immediately. Spray on 7-day intervals with a labeled fungicide to slow the disease.
DEAR NEIL: I don't know if it's nutgrass or nutsedge, but it's taking over my yard. I have tried RoundUp and vinegar on it, but to no avail. I don't want to damage my lawn.
Use a product called Image. It will not damage your turfgrass. It requires two treatments 30 days apart. The second treatment can be no later than mid-September, so the first application must be made immediately. Water it into the soil deeply, and wait patiently. The nutsedge will gradually die away. This has been a terrible year for it.
DEAR NEIL: Why would a Bradford pear turn brown in the summer then drop its leaves? This is the second year it has done it. The tree I'm asking about is in San Antonio if that helps.
That is cotton root rot. It's a soil-borne fungus for which we have no chemical control. It attacks mature trees and shrubs in areas with alkaline soils and kills them, generally much more rapidly than this. You will need to use a resistant small tree as your replacement. Options would include redbuds, tree-form hollies such as yaupon and Little Gem southern magnolias among others.
DEAR NEIL: We have young pecan trees that have very heavy crops of nuts. The trees' limbs are breaking, probably from the weight of the pecans. What can we do? Obviously we want the pecans, but the trees are going to be ruined. Also, why are the pecans falling so early? It looks like they have a fungus.
Trim 2 to 4 feet of tip growth off the individual limbs. The branches are far more important in the long run than the few pecans you'll be sacrificing. The disease is probably pecan scab. You need to treat for it in late spring and summer. This year's rains have caused large and heavy crops of pecans, many of them besieged by this disease. Affected pecans turn black and watery and fall prematurely.
DEAR NEIL: Have several fairly old native Texas cherry trees that lost all of their leaves earlier this summer. Some have sprouted out new growth, but they appear, in general, to be much less vigorous than usual. Could all of this be due to the prolonged rain earlier?
From the clues you've given me, I would have to agree with you. It would help to have a few more insights as to what the leaves looked like just before and after they fell. However, many very durable plants lost foliage due to the wet soils and extended period of high humidity. Keep watching them for a few more weeks. They'll probably get better.
DEAR NEIL: Is there such a thing as a weeping live oak? I have seen a tree that must be a live oak, but its branches hang decidedly downward.
Live oaks vary a great deal from one tree to the next. If you compare them for a few days, you'll find others that are doing the same thing. Usually, they have the finer, smaller foliage.
It's a slight genetic variation between individuals.
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.
Take a sample to a Texas Certified Nursery Professional at a retail garden center for identification. Grass burs are green initially, but they turn tan/brown as they mature, not black. For the record, you would apply a pre-emergent weedkiller (Balan, Team, Dimension, etc.) two weeks before the average date of your last spring killing freeze, then again 90 days later to prevent grassburs.
However, if this turns out to be a non-grassy weed you will need to use another type of pre-emergent, specifically one called Gallery on that same time schedule. Early September pre-emergent treatments will prevent cool-season weeds, that is, the weeds that grow during late fall, winter and early spring.
DEAR NEIL: The owner of the property behind mine has trees that are severely infested with worms. He does little more than spray the trees. The worms have fallen onto my property and have ruined my own tree. I don't think it will come back. Advice?
Your photos show webworm damage. While it was widespread this spring and summer, affected trees will definitely not be killed by the damage. The best control is to prune them out when you first see them with a long-handled pole pruner. Just nip off the ends of twigs.
DEAR NEIL: What should we do with roses that are bare because of black spot?
You can prune them back by 25 to 30 percent now to encourage strong fall regrowth and bloom. It is getting late for this trimming, however, so do it immediately. Spray on 7-day intervals with a labeled fungicide to slow the disease.
DEAR NEIL: I don't know if it's nutgrass or nutsedge, but it's taking over my yard. I have tried RoundUp and vinegar on it, but to no avail. I don't want to damage my lawn.
Use a product called Image. It will not damage your turfgrass. It requires two treatments 30 days apart. The second treatment can be no later than mid-September, so the first application must be made immediately. Water it into the soil deeply, and wait patiently. The nutsedge will gradually die away. This has been a terrible year for it.
DEAR NEIL: Why would a Bradford pear turn brown in the summer then drop its leaves? This is the second year it has done it. The tree I'm asking about is in San Antonio if that helps.
That is cotton root rot. It's a soil-borne fungus for which we have no chemical control. It attacks mature trees and shrubs in areas with alkaline soils and kills them, generally much more rapidly than this. You will need to use a resistant small tree as your replacement. Options would include redbuds, tree-form hollies such as yaupon and Little Gem southern magnolias among others.
DEAR NEIL: We have young pecan trees that have very heavy crops of nuts. The trees' limbs are breaking, probably from the weight of the pecans. What can we do? Obviously we want the pecans, but the trees are going to be ruined. Also, why are the pecans falling so early? It looks like they have a fungus.
Trim 2 to 4 feet of tip growth off the individual limbs. The branches are far more important in the long run than the few pecans you'll be sacrificing. The disease is probably pecan scab. You need to treat for it in late spring and summer. This year's rains have caused large and heavy crops of pecans, many of them besieged by this disease. Affected pecans turn black and watery and fall prematurely.
DEAR NEIL: Have several fairly old native Texas cherry trees that lost all of their leaves earlier this summer. Some have sprouted out new growth, but they appear, in general, to be much less vigorous than usual. Could all of this be due to the prolonged rain earlier?
From the clues you've given me, I would have to agree with you. It would help to have a few more insights as to what the leaves looked like just before and after they fell. However, many very durable plants lost foliage due to the wet soils and extended period of high humidity. Keep watching them for a few more weeks. They'll probably get better.
DEAR NEIL: Is there such a thing as a weeping live oak? I have seen a tree that must be a live oak, but its branches hang decidedly downward.
Live oaks vary a great deal from one tree to the next. If you compare them for a few days, you'll find others that are doing the same thing. Usually, they have the finer, smaller foliage.
It's a slight genetic variation between individuals.
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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