The Hemlock Wooly Adelgid (HWA) appears to have taken hold again and has been active all winter. This is the insect, which appears as a white cottony mass on the underside of Hemlock (Tsuga canadensis and Tsuga caroliniana) branches. There is finally some good news in the area of a biological control for HWA a scientist in the Canadian Forest service has identified a beetle, Laricobus nigrinus, which feeds on HWA, research and testing is underway. For more information check out this website: www.invasive.org/hwa/laricobus.cfm Please note - if you have infected Hemlocks, and are currently treating them do not stop. This beetle is great news for the future, but HWA can still kill a mature tree in 3 to 7 years if untreated. Horticultural Oil is a topical treatment which can be applied this month when temperatures are at least 45’ F (and not freezing for 48 hours after application) also Imidacloprid is a systemic which can be injected into the soil or tree trunk but severely damaged trees may not be able to transport the pesticide to the infected areas in this case tree removal or Hort oil is the best solution.
Winter Moth this pest is my other nemesis, and early indications are that the insect was actively breeding over the winter and the “little green caterpillars” may be out again in force this spring. Check fruit trees Crabs, Cherries, etc. for caterpillars and other pests. If you noticed a lot of moths flying around outside in November and December that was probably the cankerworm moth and the caterpillars usually start to feed on tree and shrub buds just about now. Can treat with horticultural oils or consider hiring a certified arborist.
Apply pre-emergent crabgrass killers to your existing lawn now. This stops the annual weed seeds from germinating (starting to grow). The grass we want in our lawns is a perennial (comes back every year) and the existing lawn grass won’t be effected by the pre-emergent.
Begin removing mulch from your perennial beds, and gently cut back any remaining perennial husks, you may be surprised at how many new sprouts are starting already. Also check the depth of landscape mulch, the optimum depth should be 2” to 3” deep and should not touch or cover any plant leaves, branches or trunks. Improper application of mulch can be very damaging to plants.
Remove stakes, tree wraps and guy wires from trees planted last fall. They can pose long-term problems for trees if left on too long.
Thank you to everyone who has sent in ‘Questions for Cory’, keep those great questions coming. I will try my best to answer those questions here. This question is a repeat from 2 years ago, but it is still a hot topic here in Dedham.
Q. I have a real problem with Skunks digging up my lawn, how can I get rid of the problem without dumping a lot of chemicals on my lawn?
A. Skunks, moles and voles love to eat white grubs (many of which are Japanese beetle larvae), which are feeding off your grass roots before they change into beetles and eat the rest of your garden plants. Your best non-toxic defense in this case is multi-staged. For March to May, The Mass Audubon Society recommends loosely placing fruit netting over the lawn areas under attack by the skunks, birds and mammals don’t like walking across the netting and are therefore discouraged. In the summer when the beetles are on the attack if you keep their numbers down they will produce fewer offspring. Trapping, hand picking, and even vacuuming the beetles can do this, as can encouraging their natural enemies (such as nematodes, cardinals and Spring Tiphia). In late summer and early fall keep your lawn grass longer (and soil temperature cooler), several studies have shown that the shadier cooler areas are less attractive to the grubs. And finally there is Milky Spore Disease (Bacillus popilliae) a bacteria like Bt mentioned earlier, which attacks only white grubs and is harmless to the beneficial insects in your yard, humans, mammals, birds, etc.
Questions for Cory?
Send to: Cory Landscape
PO Box 1059
Dedham, MA 02027