:How can I kill winter weeds now?
:With slightly warmer weather, it's time to check out your lawn for winter annual weeds. Spread back the dormant Bermuda grass and take an inventory of the number of green weeds present. Consider even small weeds, since these will be growing in the months ahead and will become large, flowering plants by spring.
If you have a number of winter annual weeds, an application of a glyphosate product (Round-up, Killzall, Kleeraway or Glyfos) will knock out these weeds before they become difficult to control. Products with glyphosate can be applied on dormant Bermuda grass and zoysia grass to control winter annual weeds. You can improve the control of broadleaf lawn weeds by adding a labeled rate of a 2, 4-D product to the spray mix. Adding a spray dye to the tank will allow you to see where you have sprayed and help prevent skips or double application.
When spraying, select a day when the temperatures will be above 50 degrees and the wind is calm. Glyphosate products are toxic to almost all green plants. Do not apply spray in tall fescue areas or where Bermuda has green shoots. Spray when the wind is calm to avoid drift onto evergreen trees and shrubs.
:How warm should it be to apply dormant oil?
:To curb insect problems, apply dormant oil spray to deciduous trees and shrubs. Dormant oil controls scales, aphids, spider mites, twig borers and pecan phylloxera. Apply dormant oil when the daytime temperature will be 40 degrees or higher for several hours. Follow label directions but do not use suggested dormant oil rates on evergreens. For evergreens, such as Euonymus, use the summer oil rate.
Bill Geer is director of the Oklahoma County Extension Service. His column addresses frequently asked horticulture questions. For more information, call 713-1125.