Sumi on Gardening in May, and all about Weeds

by Susan Harrris
Homestead’s Gardening Guru Gene Sumi’s talk to the Golden Spades this month was on the subject of weeds, but first, he recapped for us what we should be doing in the gardening.  Apparently a lot, because, in his words, “It’s a key month of the year!”  Here are the highlights.

Put out your summer annuals and warm-season vegetables.  For tropicals he recommends Mother’s Days, so this weekend is perfect.

For the lawn, fall fertilizing if best but if you didn’t feed your lawn last fall, go ahead and do it now.

Weigela and Azaleas in May

When flowers fade is the perfect time to prune spring-blooming shrubs that may need pruning.  Spring-bloomers include azaleas, rhododendrons, early-blooming spireas (like ‘Anthony Waterer’), lilac, deutzia, kerria, mockorange, weigela, forsythia, viburnum, St. johnswort and redtwig and yellowtwig dogwood .  IF yours are overgrown or underblooming or need pruning for some other reason, simply Google “prune” and the name of the shrub, and look for authorities with “edu” at the end.  After blooming is also a good time to feed these shrubs.

Lacebug (L); evidence of Lacebug Damage (R)

Now on the subject of pest control, Gene had lots to say about lacebugs, which are growing like crazy now and will hatch the last week of May.    Watch for them now because it’s easier to control them early – using horticultural oils and insecticidal soaps.  (Here’s a good source of identifying and treating plants for lacebugs.)

Bagworm

Bagworms, too, are best controlled now – by hand-removal.  There’s more about bagworms from Penn State.

Grubs in the lawn are already chomping away on the roots of your turfgrass and need to be treated now (if you didn’t apply a grub-killer in September, which is the ideal time to do it).  Gene says the chemical that’s effective against them – Dylox – is the one in all the products, so just shop for price.

Now about those weeds

This got our attention – Gene’s prediction that because of the super-hot summer of 2010, which produced more than the usual number of weed seeds, 2011 will be a banner year for weeds.  Oh, goody.

What are weeds?  Only the great survivors of the plant world – plants that are drought-tolerant and pest-tolerant, on top of being undesirable in the eyes of the gardener.  Actually, Gene kinda likes the looks of Henbit, but it has the nasty habit of out-competing all other plants, so even it has to GO.

Golden Spade group waiting for Gene to explain all those bottles.

One weed-killers made from organic sources is BurnOut II, made from ascetic and citric acids.  It’s nonselective, so it kills everything it touches, by the mechanism of removing the cuticle protecting the leaves.   An old-fashioned organic choice in weedkillers is vinegar, especially the type with higher concentrations of ascetic acid than the usual vinegar we use in cooking (which is only 5 percent).

Another nonselective weedkiller is Roundup, which contains the synthetic ingredient Glyphosate and works systemically.  Gene recommends it for the really tough-to-kill problem plants, like bamboo, because it’s effective, yet breaks down quickly and is relatively safe among the choices of herbicides.  Roundup’s Poison Ivy product also contains a brush-killer for heavy-duty work, which means it’ll kill even woody plants like shrubs and thick vines.  Brush, vine and stump-killing products are synthetic weedkillers that are dabbed onto stumps with a brush, and they’re very effective in these situations when nothing else will really work.

So, Professor Sumi, how DO systemic herbicides work?  He says they pass through cells wall and eventually reach and kill the roots, which causes the whole plant to die gradually over several days.  Warm temperatures are needed for this movement through cells (translocation) to happen.

Insect photo credit – Oklahoma State.

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