Hemlock and woolly adelgids
Always love your column. A few years back, I even submitted some stuff to you, and I was thrilled to see it in print. Now I have something really important for you. I have a beautiful hemlock in my yard. Recently, I noticed some white stuff on it, so I shot a photo out to our county agent, Karen Bernhard. She came back with the bad news. It is hemlock woolly adelgid. Very bad indeed! If you drive up the turnpike to the Poconos, you will see thousands of dead hemlocks killed by this pest. There must be thousands of hemlocks in our parks or peoples’ yards. People need to pay attention to them and get professional help if they see signs of the adelgid. It is really a bad news pest.
Thanks for your great work.
— George Smith
I am quite familiar with this particular pest. Our previous home in Palmer Township had a hedge of hemlock trees (tsuga canadensis) on three sides of the yard. Fran noticed the white stuff on a few branches, did the research, and treated the trees with the recommended treatment at the time, Merit. We held the nasty little pests at bay for a few years but never got rid of the problem. The chemical was applied in the soil at the base of the trees.
More current information can be found in the Penn State Extension article, Integrated Approach to Hemlock Woolly Adelgid Mitigation.
The process includes properly timed chemical applications (horticultural oil, insecticidal soap, imidacloprid, or dinotefuran), keeping trees well watered to avoid stress, removing badly infested trees and selecting alternative trees until a better, more resistant hemlock is developed. Biological controls are still being investigated as far as I could research.
Hemlock: A poisonous weed?
Several weeks ago you published an article telling about nasty weeds in the yard, one of which is Hemlock. Lo and behold it arrived in our yard. At first it looked kind of pretty, i.e., Queen Anne’s lace, but it ran rampant. Down to Home Depot for the Round Up and a sprayer and it looks like maybe we can subdue it for you.
1. When it finally dies can I mow it or weed whack it? 2. It is supposed to be poisonous, how? Respiratory, skin, eyes etc.? 3. Will it come back next year? 4. Will it require repeated treatments of the herbicide?
Thanks for the help.
— Dan M.
Dan is referring to poison hemlock (conium maculatum), a biennial weed that does, as Dan mentioned, resemble members of the carrot and parsley families such as Queen Anne lace, in its second year. The entire plant is toxic to humans and other animals with the highest concentrations of the alkaloid poison found in the roots and seeds. Poisoning can cause muscle paralysis and skin irritation.
Chemical control should be directed to the first year growth — low, rosettes. While chemicals are effective, I cannot recommend their use. Post-emergents herbicides include: diquat, pelargonic acid, glyphosate (all are non-selective), and 2,4-D.
Hand pulling or digging is difficult because the plant has long tap roots and contact with the plant has another unpleasant surprise: the sap is a skin irritant. Wear gloves and protective eye gear if you plan to dig or pull out hemlock. The plant debris should be bagged and discarded. Do not compost it. Note that using tools such as a weed whip will work but the equipment must be cleaned after use to wash off the toxins and skin irritants. See the Penn State article, Poison Hemlock.
Second year growth is tall, up to six feet, the flowers are white and appear in clusters, usually in August. The hemlock plant has a smooth stem with red or purple spots. Queen Anne’s lace has a hairy stem.
A further suggestion is to make sure that the plants do not go to seed. It is likely that whatever process you use will require diligent work for several years to get control of this problem. Eradication is not possible as it is unlikely that you will remove every part of the root and there will be seeds from previous years in the soil.
Repeated mowings can offer some control by eliminating the flowers and reducing the plant vigor. Remember to clean the blade.
Week in the garden
Planting: Start sequential sowing of crops like beans, radishes, lettuce, and spinach to create a longer harvest season. Set out tomatoes when the weather warms to at least 50 degrees at night. Wait a few weeks before setting out basil, eggplant or pepper transplants. Start seed for: Baby’s breath, cosmos, zinnias, salsify, eggplant, summer squash and winter squash. Direct sow: Snap, bush and pole beans, cantaloupe, melons, cucumbers, rhubarb, summer and winter squash. Continue sowing: Celeric, celery, cabbage, carrots, collards, bunching onions, onion sets, parsnips, and Swiss chard. Plant or pot up summer bulbs and tubers such as dahlias, cannas, calla lilies, and caladiums. Plant bare root trees and shrubs. Make sure the soil is dry enough to work — don‘t dig or plant in mud. Buy annuals for containers, annual garden beds and to fill in bare spots in perennial or shrub beds. Follow your schedule for starting seeds. Check packets for instructions such as start indoors four weeks before last frost date.
Seasonal: Start pinching back chrysanthemums and asters to promote bushy growth and more flowers. Continue to pinch back new tips at two-week intervals until early July. As the weather warms, ease out your plants that wintered over inside. Start with an hour or so on a warm day and increase outdoor time until the nights are regularly in the 50-degree range before leaving them out for the season. Visit nurseries as they open for inspiration as well as new plants. Shop for summer bulbs as well. Apply a top dressing of compost to lawns and beds. Test soil for new beds, Retest soil in poorly performing areas or those that haven’t been tested in the last 3-5 years. Cut back ornamental grasses. Divide when you see new green growth. Divide hostas and daylilies. Prune and divide perennials that bloom in late summer or fall. Prune back and clear out dead, diseased or unattractive stems from perennials and shrubs, but not those that flower in the spring. Please check proper pruning information for each plant and prune as needed and recommended. Apply spring and summer mulch, two to three inches deep and placed a few inches away from foundations, tree trunks and other plants. Fluff mulch and add more if necessary. Apply corn gluten based weed control in the garden and establish a schedule for reapplication, usually at four to six week intervals
Lawn: Now: Dethatch, seed or overseed lawns. Apply broadleaf weed control and complete sod projects. By mid-June: Apply spring fertilizer treatments. Apply preemergent crabgrass control regularly at four- to six-week intervals. Fill in holes and low spots in lawn.
Chores: Water any recent plantings anytime we experience a week with less than an inch of rain. Fix damaged screens and garden hoses. Note damaged caulking around doors and windows. Dump standing water and remove anything that may collect rainwater to help control mosquito populations Provide deer, rabbit and groundhog protection for vulnerable plants. Reapply taste or scent deterrents. Clean and fill bird feeders regularly. Clean up spilled seed and empty hulls. Dump, scrub and refill birdbaths at least once a week. Consider setting out nesting materials if you have them. Clear gutters and direct rainwater runoff away from house foundations. Tools, equipment, and supplies: Store winter equipment and replace or repair as needed. Check spring/summer equipment — repair or replace damaged or worn out tools. Check power tools and mowers and send for service if needed.
Safety: Clear lawns of debris before mowing and make sure pets, children and others are well away from the area being mown. Store garden chemicals indoors away from pets and children. Discard outdated ones at local chemical collection events. Photograph storm damage before clearing or repairing for insurance claims and file promptly. Any time you are outside and the temperatures are about 50 degrees or warmer watch for tick bites. Use an insect repellent containing Deet on the skin. Apply a permethrin product to clothing. Wear light-colored clothing, long sleeves, hats and long pants when working in the garden. Stay hydrated. Drink water or other non-caffeinated, nonalcoholic beverages. Even in cold weather, apply sunscreen, wear hats and limit exposure to sun. Wear closed-toe shoes and gloves; use eye protection; and use ear protection when using any loud power tools.
Sue Kittek is a freelance garden columnist, writer, and lecturer. Send questions to Garden Keeper at grdnkpr@gmail.com or mail: Garden Keeper, The Morning Call, PO Box 1260, Allentown, PA 18105.
