Question

marigold disease   Hi Mellisa my potted marigold are wilting due to reasons unknown to me. I live in North India with temp around 22-30 C.My potting medium is organic compost and garden soil in equal ratio.On recommendation by a local garden shop i tried dimethoate spray but it is not working even after twice a week spraying for two weeks.I do not see any insects on the plant.What can be the likely cause.
Warm Regards
Dr Shailesh Mehta

Answer
Dear Dr. Mehta, The most likely reason why your marigold is wilting is because it has become infected with a bacterial wilt, which unfortunately is incurable.  The curious thing is that generally with wilt diseases the plant usually dies within a week, so it would be unusual for your plant to still be alive two weeks later.  So it could be possible that your plant has some other fungal disease.  The dimethoate spray would definitely have killed any spider mites that might have been affecting it which is the only other likely problem with marigolds.  When you get this reply, if the marigold is still hanging on, then I recommend spraying it with NEEM, an organic compound which is available in India, and it kills insects, fungus, and mites, and just using NEEM can replace all your house plant and garden spraying.  In that way, if it is another fungus, it should improve, and if it is affected with wilt then it won't survive anyway.  One thing I would like to mention: since this is a potted plant, make sure that there is no water standing in a dish under the plant after watering, make sure it is in the sun, and make sure that you let it dry out almost completely before watering.  I wish this were an instance where I could absolutely tell you that it is or isn't wilt and definitely to throw it out and plant something else, but if you spray with the NEEM and it doesn't improve, then I would throw it away and replant a different plant.  Good luck to you.  (By the way I have family in Dehra Dun and New Delhi!) Melissa