In the Grow (Q & A)

The following question and answer columns are currently written by B. Rosie Lerner, Purdue Consumer Horticulture Extension Specialist and are distributed to news media around the state by the Purdue University Agricultural Communications. Columns from June 1995 - January 2006 were authored by Bev Shaw, Advanced Master Gardener.


Many possible reasons for early loss of white oak leaves / Marestail Control


Q. I have a white oak tree that lost about half of its leaves to a varmint. I’m guessing June bugs that were in a bunch about 15 feet away. The tree did not put out any new growth except late in the summer on the end of the tallest limb. Meantime, a new tree sprung up. I’ll include some pictures that will show the leaves and their color. I have no idea what flavor […]


Spider lily likes moist conditions – but not too much


Spider lily likes moist conditions – but not too much Q. This flower was in my yard when I bought my house, and it was the most beautiful plant I have ever seen. It bloomed for the first two years that I was here, but for the last two it hasn’t. It has become so weak that the stems don’t stand up straight anymore and grow pretty much laying down. Do you know how I […]

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Jury still out on use of rubber mulch


Q. Our HOA is considering using rubber mulch in a large area. In your experience, what is the up side or down side? I have read that as it deteriorates the chemical and all ingredients break down and go into the soil. Any thoughts?  – LK, Lafayette, IN A. This is a really great question that unfortunately does not yet have a clear answer. There are many questions remaining regarding the long-term safety of using recycled shredded or crumb […]


Larch Needle Blight/White Ash Woes/Top-setting Onions


Q. I have noticed lately that our three big, lovely larches are losing needles on their bottom half. The needles have a banded pattern of color, and I fear larch needle blight. How can I confirm or reject this hypothesis? Is there anything we can do to treat them? – JC A. Specific diagnosis will require more than just these photos. I recommend sending samples of your trees to the Purdue Plant and Pest Diagnostic […]


Pricklypear Cactus Wanted and Unwanted


Q. How do I keep cactus out of my yard? They grow somewhat flat on the ground and have yellow flowers. I have sandy soil – I call them sand cactus. I keep digging them up, but can’t seem to get rid of them.  – D.C. A. The eastern picklypear cactus, Opuntia humifusa, is native to most of the U.S. including Indiana and is considered beautiful and valuable by many. But it certainly can be a […]


Cull Rotted Bulbs


Q. I’ve been raising alliums for 20 years. Some years I’ve left them in the ground over winter, but most years I lift them when the stems dry up and replant them late September –  early October. This year I lifted them and most were rotten. I’ve never seen this before. I had 47 to dig this year and only got a dozen to replant this fall. I hope the pictures show the little white maggot looking […]


Decrease powdery mildew through prevention


Q. Is there any way you could help in figuring out what is wrong with our lilac? – C.B. via email. A. Lilacs are quite susceptible to a fungal disease called powdery mildew, which causes a grayish-white, powdery coating of spores and fungal structures on the surface of leaves, stems, flower petals and fruit. According to the Purdue Plant and Pest Diagnostic Laboratory, the best method of control is prevention. Practices that will decrease the severity […]


Warm, wet conditions prime for algae


Q. For the last few years we have noticed some green blobs on our gravel drive. It only grows in size when it rains and dries up and turns black when the weather is sunny. It looks like turkey droppings and feels like jelly when wet. It is very unsightly and gets tracked into the house. We never saw this stuff until the last few years and only on limestone gravel. It seems to grow […]


Leaf galls common to oak trees


Q. We have a pin oak tree that is approximately 30 feet tall. On the north-facing side of the tree there are many wilted leaves, and there are many balls of strange growth. Pictures of the leaves and the balls are attached. Can you help to identify the problem and any solutions that we need to pursue? – M&L W, Indianapolis A. My best guess is one of the many leaf galls common to oak […]


Ugly scale on hollyhocks could be fungal rust


Q. The last three years I have had scale on my hollyhocks. They just start to bloom, and the scale appears and they die. Is there something I can use to get rid of the scale? After they start to die, I clean up everything and burn. – I.T., Paoli, Indiana. A. I wonder if you might be referring to hollyhock rust, a fungal disease that commonly affects hollyhocks. The rust-colored blotches can resemble scale […]


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