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Garden Doctors: Debugging roses

<strong>Harold asks:</strong> <em>The petals on my Abraham Darby rose have light brown marks on them and some of the buds have failed to open completely. The bush appears very healthy, but when I cut some of the blossoms to bring inside, I noticed these minute insects busily crawling over the individual petals.</em>

<em> Can you tell me the name of these insects and how to control them without spraying a lot of chemicals?</em>

These "minute insects" are called thrips. Thrips are difficult to control because they continually migrate from other plants or from rose bush to rose bush. They seem to be more attracted to white and pastel colored varieties of roses.

Their complete life cycle occurs in 2 weeks, so populations increase rapidly. The first plan of attack is to remove and destroy infested buds and blossoms by enclosing them in a plastic bag and discarding the collection in the garbage container. (It is not a good idea to throw away diseased clippings in the compost pile.)

Thrips also feed on nearby plants and grasses, moving from these plants to roses. Keep the surrounding area near your roses free from grasses and tall weeds.

Insecticidal soaps or pesticides that contain pyrethrum can be used as part of the control program. The label will give instructions for thrip control. The release of beneficial insects such as parasitoid wasps and green lacewings may also provide some control.

<strong>Mimi asks:</strong> <em>How can one tell if it is time to repot a houseplant?</em>

It is time to repot plants when the roots start circling the bottom of the container and actually begin to emerge through the drainage hole. Observe the condition of the root growth by carefully removing the plant from its container. If it needs repotting, wash the soil off of the roots, gently loosen the roots and repot in a slightly larger pot filled with fresh potting soil. Water in well and do not fertilize for a while until you feel the plant has become adjusted and is thriving in its new home.

There are some plants that prefer to be rootbound and can be left in the same container for years. An example of a plant that can survive for years in the same container is Sansevieria trifaciata, commonly known as Mother-in-law tongue.


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