Garden, Lawn & Landscape Q & A

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It has been another busy season in the garden, lawn, and landscape of Catawba County. We have had some interesting questions and challenges come into the extension office that offer insight into new pests that have moved into our county and a major change in fertilizer recommendations for your lawn.

Q: I read an article about a weed called giant hogweed that said people are getting badly burned by the sap in this plant. Is it in Catawba County?

A: Giant Hogweed has recently been found in Watauga County but it has not been confirmed in Catawba County. If the sap of this plant makes contact with your skin it can blister, burn, and even scar you permanently. The sap contains a compound called furocoumarin, which helps the plant fight off disease. However, when giant hogweed sap makes contact with skin and that skin is then exposed to light the furocoumarin will activate and cause serious skin damage. Hogweed is a very distinct weed, growing over 10 feet tall with flowers that look like those on wild carrot. Please call our office or send us a photo if you suspect that you have giant hogweed on your property.

Q: Some of my shrubs and trees have become overgrown this summer. Can I do some pruning now to improve their appearance?

A: We do not recommend that you prune any woody plants in the fall. Any pruning now will result in young, tender growth right before cold weather. That young growth will be most vulnerable to winter damage and subsequent pathogen infection of the damaged tissue. Wait until February or until after spring bloom (May – June) for the early blooming woody plants like forsythia.

Q: Has waterhemp arrived in Catawba County?

A: Yes. Anelle Ammons, our Agriculture and Natural Resources Agent discovered the weed waterhemp this summer. This weed has been moved from the Midwest on equipment. Unfortunately there are some biotypes of waterhemp that are resistant to several different herbicide families. Waterhemp is a cousin to pigweed, Palmer amaranth, and spiny amaranth. Unfortunately, all of these weeds can cross-pollinate and pass herbicide resistance to their offspring.

Q: I had several patches of grass in my lawn die. Can I re-seed those patches now?

A: We recommend that you re-seed tall fescue (the dominant lawn grass type in Catawba County) in mid-September to early October. Before doing that be sure to follow these steps: take a soil sample 4 weeks before re-seeding, kill everything in the patch that need to be re-seeded, add any amendments that your soil test results suggest, lightly till the soil or aerate it, over-seed your grass seed, and irrigate daily for 3 weeks for optimal seed germination. The grass seed must make contact with soil and moisture or it will not germinate.

In the past, the NC State turf program has recommended that nitrogen fertilizer only be applied to a tall fescue lawn in mid-Sept to mid-November and again in mid-Feb to minimize the fungal disease brown patch. That is no longer the recommendation! Recent research does not show any relationship between nitrogen applications and brown patch. In fact, if your lawn is starved of nitrogen in the summer, it may be more susceptible to this disease. The new recommendation is to apply a quarter pound of nitrogen per 1000 square feet every 6 weeks once the soil temperatures are above 50 degrees (from mid-February to early November depending on weather). A couple of light summer applications may help your grass defend itself from fungal disease. However, increased grass growth from additional nitrogen may make your lawn more vulnerable to drought if you are unable to irrigate.

I realize that this recommendation is a little complicated and quite different from previous lawn care recommendations. Please feel free to call our office at 828-465-8240 if you have any questions. Be sure to attend some of the many gardening classes that we are offering at libraries and our office throughout the year. There are still a few slots seats available for the 2019 Master Gardener℠ volunteer class – call our office to register before the class fills.