Q: I was told that sunflowers produce toxins in the soil they grow in. Will these gentle giants destroy my surrounding plants? Do the toxins build up over time? Angela Burrage, Chatsworth
A: When one plant reduces other plant's growth, it's called allelopathy. Many people believe black walnut trees inhibit the growth of some kinds of plants around them but research on if (or why) this happens is inconclusive. It may be just a garden myth. There are a couple of studies that concluded sunflowers inhibit broadleaf plants nearby. The conditions of the studies were not similar to garden situations, so I'm not sure the conclusions can be applied to your garden. In any case, the inhibition was mild. I'd say you have nothing to worry about unless you have lots and lots of sunflowers.
Q: How do I prevent fescue grass from growing in my bermuda grass sod yard? Clint Hight, email
A: The easiest way is to consistently mow the bermuda grass low. Fescue really hates being mowed lower than a couple of inches but bermuda loves it. Fertilize every six weeks to stimulate a thick stand of bermuda. Imazaquin (Image for Nutsedge) is labeled for use to remove fescue from bermuda. Read and follow the label exactly.
Q: Our favorite rose got the rose rosette crud. Does it need to be burned after removal? Melissa Feuer, Covington
A: You don't need to burn it. The best thing to do is to clip the rose bush into pieces small enough to be put into a bag that's taken to a landfill. Don't use a blower to clean up afterward. It could disperse the mites that spread the disease. Use your hands to gather debris and put in the bag.
Q: Does it make any sense to control grubs with insecticide in an effort to make moles leave my lawn? Thomas Skarbek, email
A: In a word: no. Killing grubs only makes moles search more frantically for other things to eat, such as earthworms. They also eat soil-dwelling springtails and other insect larvae. In my opinion, mole traps and poisons are too complicated and exacting to use. I maintain that the best way to control moles is to persistently mash down their tunnels so they find other lawns to hunt food.
Q: I harvested one lone filbert nut on my tree. When will the tree mature and give me more? Pam Fennimore, email
A: Congratulations! You have accomplished the typical yield from a single filbert tree. The reason is that filberts (and hazelnuts) have male and female flowers on the same plant but the pollen is self-incompatible. Filberts require another tree nearby to provide appropriate pollen. If you plant another tree, let me know how your yield increases.
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