Gardening Tips: February Question and Answer

— Written By and last updated by Chrissy Poole

Q: When is the best time to put down a pre-emergent herbicide for crabgrass control?
A: The best way to control crabgrass and other summer annual weeds is by using what is called a pre-emergent herbicide. A pre-emergent herbicide prevents the weed seeds from germinating, effectively preventing them from coming up. This is the most effective way to control crabgrass because it is a very difficult weed to kill without damaging the lawn once it has come out of the ground. Timing of the herbicide application is very important, if you wait to long you’ll have poor coverage and if you start to soon it won’t last long enough into the summer. Usually the best time to apply in Halifax County is about the middle of March, during the bloom period of Forsythia. Herbicides containing the chemicals benefin, pendimethalin, and oryzalin are the best options for control. Many different herbicides made by a range of companies contain these chemicals, so look for something listed as a crabgrass preventer containing one of those chemicals. Follow all label directions of the product for application rate and method.
Q: When is the best time to apply lime?
A: Unlike fertilizer, which should only be applied at certain times of the year, depending on the plant it is being applied to, lime can be applied any time of year. Lime simply raises the pH of soil, making nutrients in the soil more available to plants, it does not actively encourage growth like fertilizer does. Therefore it is ok to add it now when plants are dormant, or in early spring as plants are beginning to grow, or any other time. Lime is also slow acting, so in many ways it is beneficial to add it early. For example, if you plan to have a vegetable garden this year, applying lime to the garden now means that the soil will likely be in better shape during the summer than if you were to wait to apply lime until June. The amount of lime you apply should be based on a soil test. Contact Cooperative Extension for directions on how to do a free soil test.
Q: Every year my roses get eaten up by bugs and are covered in spots. Is there anything I can do?
A: For as beautiful as roses are, they sure have a lot of problems. Japanese beetles, aphids, thrips, black leaf spot, powdery mildew and many more insects and diseases can be major problems for rose lovers. Controlling any one of these pests can be difficult, but trying to control them all is a lot of work. Rose growers need to plan ahead and be ready to act to control these problems. First, take the time in the spring to prune your roses. Thinning out extra branches and removing older growth will help increase air flow through the plant, which is always important in preventing diseases, and may remove some infected tissue. Fertilize and water roses appropriately and make sure they receive a lot of sun so they grow healthy throughout the year. And finally, try to anticipate what pest problems you might have and decide ahead of time how to act if they arise. Japanese beetles are always difficult to control, but picking them off and placing in soapy water (be prepared to repeat everyday as new beetles arrive) is an effective, if time-consuming control option. An alternative is to spray with an insecticide such as Orthene, Sevin, malathion, permethrin, or pyrethrins. Again, be prepared to repeat but make sure to follow label directions. Should black leaf spot or powdery mildew appear, you can treat by alternating sprays of chlorothalonil (Daconil) and myclobutanil (Immunox) every 7-10 days until the problem is under control. Again, follow all label directions. There are rose sprays on the market that are a mix of fungicide and insecticide that offer good baseline control for many common insect and disease problems, but you will likely need to alternate these with the listed products above for best control.
Matthew Stevens is the horticulture extension agent for Halifax County Cooperative Extension. If you have any questions about this article or other aspects of your home gardening, please contact Matthew at 583-5161 or matt_stevens@ncsu.edu.