Identify the insects on your plants before treating them

It is important to identify the insects on your plants before treating with an insecticide to determine whether or not the insect really is a problem. If it is, try to assess whether the damage being done warrants control. The presence of insects feeding on the plants should not warrant automatic treatment. Some insects are beneficial and help control other insects naturally. If an identified pest is causing significant damage, it is important to use a correct control with proper timing. If a variety of treatments are available, use the least toxic control possible.

• If the plants growing in your containers or baskets are looking stunted or have leaves that are yellowing, they may need supplemental fertilizer. The frequent watering required for containers and baskets can leach nutrients out of the growing medium.

Use a liquid fertilizer as needed to perk them up. It is best to fertilize containers and baskets when plants are moist and not dry. Fertilizing plants that are very dry can result in damage to the plants' roots.

• If the new growth at the tips of your pine's branches has turned brown, a disease called Diplodia tip blight may be the problem. It is too late to spray fungicides now, as infection occurs in the spring. Prune out dead tips in dry weather to reduce the spread of infection. Disinfect pruners in between plants when pruning out diseased branches.

• It is important to identify the insects on your plants before treating with an insecticide to determine whether or not the insect really is a problem. If it is, try to assess whether the damage being done warrants control. The presence of insects feeding on the plants should not warrant automatic treatment. Some insects are beneficial and help control other insects naturally. If an identified pest is causing significant damage, it is important to use a correct control with proper timing. If a variety of treatments are available, use the least toxic control possible.

• Crabgrass is visible in lawns now and can be identified by its wide leaf blade and light green color. You will see it growing in stressed areas of the lawn such as driveway and walk edges and in lawns that are mowed too short. Crabgrass is an annual weed that begins flowering and setting seed in July. Manually remove crabgrass now to prevent seed production and more crabgrass next year. The best way to prevent crabgrass is to maintain a healthy lawn that is thick and outcompetes and excludes crabgrass. Mow your lawn to 3 to 3 1/2 inches to promote a deep root system in your grass, which will enable it to better withstand stress and remain dense.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.