“Ask the Plant and Pest Professor” is compiled from phone and email questions asked of the Home and Garden Information Center (HGIC), part of University of Maryland Extension, an educational outreach of the University of Maryland.
Question #1: What time of the year should I be putting lime down on my lawn? Also what kind of lime do you recommend? Thanks
Answer #1: Before applying lime you should do a soil test. Soil testing will determine if you even need to apply lime and if the pH is low the results will indicate how much lime to apply. Lime can be applied just about any time of the year but fall is an excellent time for lawn tasks. Look for agriculture lime (calcitic limestone). Dolomitic lime contains calcium carbonate and magnesium carbonate and is recommended for raising the pH on low magnesium soils. Pelletized lime is similar to agriculture lime, but is easier and neater for homeowners to apply than powdered lime. Look on the homepage of our website given below for information on soil testing.
Question #2: I came home from vacation to find the leaves of my very-productive cucumber plants looking mottled and appearing to have a white coating on them. What can this be and is there something I can do to salvage the plants?
Answer #2: Sounds like your cucumbers are infected with powdery mildew, a common fungal disease that affects cucurbits. This disease is favored by warm weather and can be destructive in dry as well as wet seasons. Once plants are infected they cannot be cured. Spraying with a copper fungicide or horticultural oil labeled for powdery mildew may slow down the infection. While plants usually do not die, they are weakened by the infection which reduces yields. Prevent the disease next year by doing a thorough clean-up of your garden in the fall, plant powdery mildew resistant varieties in an area with good air circulation, provide ample spacing between plants and avoid overhead watering.
Question #3: My father-in-law wants to dig up and give me two dogwood seedlings that have grown in his yard. I do have plenty of room to plant them but I was wondering what the best time of the year is to do this. He is thinking the fall but I wanted to check.
Answer #3: Correct timing does play a role for the successful transplanting of dogwood seedlings. Fall is a good time to plant but transplanting certain tree species like dogwood, red maple, cherry, hawthorn and zelkova should be done in spring. Typically this is in March when the ground is workable. Keep the seedlings watered, especially during dry periods, for the first two years after transplanting.
To ask a home gardening or pest control question or for other help, go to http://extension.umd.edu/hgic Or phone HGIC at 1-800-342-2507, Monday through Friday, 8 a.m. to 1 p.m. Follow us on Facebook and Twitter.