Hi all, My rosemary plant lives on my window sill outdoors and has recently started getting a white, sticky coating around the stems of the shoots. If you click on the photo, you'll see that the bottom left shoot is covered in this white stuff, whilst the top right shoot is starting to get covered in it. Any idea what this is and how to treat it? Thanks very much!
I've seen similar things with wooly aphids, but never on rosemary, or perhaps a fungus although I've never encountered a sticky one before. I'd reccomend making up some chamomile tea and dousing the whole plant with it (cool, of course) - if it's fungus or aphids, that will help it quite a bit without hurting you or the plant.
You might try a quick spray with a mix of one teaspoon baking soda dissolved in one litre of water. It won't harm any plant I know of, but it will knock down the fruiting bodies of a number of fungi, including many plant mildews. If it's a fungi, the baking soda may slow it down quite a bit, possibly remove it. I'd also try to swipe a bit of that white stuff off with a Q tip, just to see if it will come off. If it does, it might, maybe, be mealy bug. I've seen one or two plants with so many mealy bugs on them that they looked a bit like this picture, though I'd be surprised if it is mealies. I have also seen something very similar on a number of Ninebark shrubs in a townhouse development where my Mom lives. Looks terrible but does not seem to be fatal, at least, not so far.
