Upper South

August, 2012
Regional Report

Favorite or New Plant

Prairie Rosinweed
With repeated hot and dry summers, our desire to add more drought-tolerant plants to the gardens increases. Prairie plants, which so often have deep tap roots, will be among those that come to the fore. One of the most dramatic of our native plants is prairie rosinweed or prairie dock, Silphium terebinthinaceum, with the one common name referring to the aromatic stem resins. The plants form a clump of huge oval to heart-shaped, dark green leaves to 2 feet long. In midsummer, thin flower stalks rise to 8 feet, topped by 3-inch wide yellow, daisy-like flowers, with the seed heads attracting birds, especially goldfinches. There are no serious insect or disease problems with prairie rosinweed, but you must be patient as the plants are slow to establish, sometimes taking two or three years to begin flowering.

Clever Gardening Technique

Safe Controls for Japanese Beetle Grubs
Among the most damaging of garden insect pests is the Japanese beetle. Controlling these voracious pests requires a two-pronged attack, one for the beetles and another for the young grubs, the first stage of their life cycle. These beetle grubs are actively feeding mainly on grass roots from midsummer into fall, making this the ideal time to control them. There are three biological controls available that are safe for the environment. These include milky spore, a bacterium called Bacillus papillae; another naturally occurring bacteria, Bacillus thuringiensis japonensis (Btj); and a beneficial nematode, Heterorhabditis bacteriophora. Of these, only the nematodes and milky spore are readily available commercially.

Several years ago, I chose the nematode approach, treating as much of the lawn as I could afford. One criteria for correctly applying the nematodes is to follow up application with repeated watering, so water costs and hose reach was another consideration for the areas to be treated. Because I live in the middle of pasture fields, which provide more habitat for the grubs, I was not optimistic. Although the water bill was staggering, the results have been well worth the cost and effort. I still have some beetle damage, but the population has been significantly reduced.

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