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by Rett Davis | |
Gardening Q&A by Rett Davis appears in
Alamance County's daily newspaper, The Times-News,
every Sunday in the Accent section. Each week's installment is
posted to this
website, beginning with January 1998. Scroll to the bottom of
this page to navigate to other Gardening Q&As. Please contact
Rett via e-mail with questions
or
comments in regard to this column.
Answer:
You are seeing the results of the spruce spider mite. These insect-like pests are active in early spring and the fall. During the summer months they are in the egg stage. During late winter and early spring these mites feed on the needles of your spruce and damaged the needles. The damage from their feeding appears months later during the summer. Spraying for these pests now is pointless. You must spray at the end of winter with an insecticide in order to control them. This is when most of the feeding takes place as well as reproduction. Spruce spider mites are the most destructive mite pest of ornamental conifers. I would start spraying in late March and again in April with either a horticultural oil (Volck, Ultra-Fine Spray oil) or Isotox. Two to three sprayings will be needed at 2 week intervals. Repeat this every year that you intend to grow dwarf Alberta spruce.
Question:
I have just noticed that many of my Leyland cypress are infested with bagworms. Over half of the tree appears dead. Are these trees worth spraying and saving?
Answer:
In my opinion they are ready for the firewood pile. Leyland cypress do not recover well from severe infestations of bagworms. I would consider 50% damaged trees ready for removal. Even if you kill the bagworms the tree will remain unsightly and of little landscape value. If you grow Leylands in your landscape, monitor them each summer for the presence of this insect pest.
Question:
I have a two year old weeping cherry tree that I paid way too much for but it is my favorite tree. I noticed several weeks ago that there was a small web forming in the branches. Now the tree is completely leafless. Is my tree dead?
Answer:
The tree should be alright. Fall webworms have been active for at least 4 weeks now. I first noticed them the last week of June in my persimmon tree. They also like pecans, cherries, and sourwoods. The fall webworms actually spin a web around the leaves that they devour. This is a cosmetic pest. By that I mean they do not damage the trees they feed on. Healthy trees will be fine. Next year you can either hand remove the worms and webbing if you catch them soon enough. You can also dislodge them with a broom or strong spray from the garden hose. Insecticides can be used. Insecticides work best when the caterpillars are young or just getting started. They can be controlled with Sevin, Isotox, cyfluthrin, or malathion. This insect overwinters as pupae in their coccon. In the spring the pupae becomes a moth and their cycle of life continues once more. They will be back.
Question:
After this drought it has become more obvious that my yard is full of wiregrass. I want to get rid of it all before I reseed with fescue this fall. How is the best way to rid of wiregrass in my lawn?
Answer:
I will tell you that it is not easy. Most homeowners fail to get it all killed only to find that it appears again the next year in their new lawn. Because this grass spreads by both above ground stolons and rhizomes underground, it often goes beyond the obvious infested area. Allow the wiregrass (bermuda) to go unmowed for at least 2 weeks to develop more leaf area. Spray the wiregrass with a 2% solution of Roundup. If you have a significant area to spray, homeowners need to purchase the Super Concentrate of Roundup. Roundup Pro and Roundup Ultra is more economical for those with large areas to spray. The ready-to-use solutions are just to weak. Read the label to determine how much Roundup it takes to make a 2% spray soltuion. Use a measuring cup or spoon to make the correct mix. Thorouhgly spray the grass for uniform coverage. You t have to wet the leaf not saturate it. Allow 3 weeks for the chemical to work. Repeat again if needed and to get areas you missed.
BAGWORM ALERT
Bagworms are fast approaching their last instar or growth spurt. They have potential for inflicting significant damage to conifers and junipers. You must treat now because in just a few weeks feeding will stop for the year. Although the bags will still be attached to the tree or shrub, insecticides will not work if you wait much longer. Therefore scout and spray now if an infestation are found. Hand removal works well too.
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If you have any horticultural questions, please direct them to Rett Davis