12 June 2007

Monarda Bee Balm Bergamot, Aphids and Thrips

This is a single plant of Monarda or Bee Balm or Bergamot - whatever name you prefer, she is a beauty every year. I started it from a pack of seeds 6-years ago. The name on the pack that attracted me was Bergamot because that's the flavoring in Early Gray Tea. The leaves make thirst quenching iced tea. The plant has been divided over and over again to give roots to friends and to plant around the yard. It needs to be divided again this year.





Here's a closer photo of the petals. Not visible is the constant covering of honey bees, butterflies and moths.

APHIDS
Gnarled, distorted, arthritic looking leaves can be caused by aphids, according to plant pathologist Margery Daughtrey at Cornell University. Link here to full article.
Check the underside of curled plant leaves and stems for signs of insects. I start treatment by drenching the leaves and stems with a few drops of dish soap in a gallon of water. Use a paper towel or other disposable cloth to gently wipe off the dead insects. If you have to resort to using a chemical treatment try to do it in the evening hours after all the beneficial insects have stopped pollinating.
Daughtrey says foliar problems on impatiens can be some of the hardest to diagnose. Leaf spot diseases on impatiens can be caused by fungi (Alternaria, Phyllosticta and downy mildew), bacteria (Pseudomonas) and viruses (impatiens necrotic spot virus). Keeping foliage dry can help control several of these diseases. Water the soil and roots not the leaves and flowers.

HERE COME THE THRIPS
Thrips pierce plant cells resulting in deformed buds, flowers, leaves and shoots. They leave behind silvery flecking and small black droppings can be seen.

Thrips spread impatiens necrotic spot virus (INSV) and tomato spotted wilt virus (TSWV) as they move among plants. Because thrips are so small and prefer to hide in flowers and buds, sticky cards need to be used to detect the thrips before their feeding damage is evident.

There is no cure for tospovirus-infected plants so use sticky cards to detect thrips before they start feeding. Spraying should start if you find as few as 10 thrips on the sticky card per week. Sticky cards can be as simple as Vaseline on a bright yellow plastic plate.

The link above has a full article with photos of plant damage from several sources (virus, mites, leafminers, etc.) so you can diagnose problems you may be seeing in your garden.

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