4

Something is killing my plant. The leaves are loosing their colour. On the branches, there is a white, stripy discharge that's slowly taking over the entire plant. Can someone identify this and tell me what I can do to heal my plant?

Some photo's (for scale: the branch is about a finger thick): The leaves The infested bark Close-up of the leaves Close-up from the bark

5

Edit: After a tip from Bamboo and a close up picture this looks like a scale insect. Most likely this is oyster shell scale

Control can be done in a number of ways which I list below:

  • take a soft scrub brush soaked in 5 ml of soap to 1 litre of water and scrub them off the affected areas. Repeat three times at 7 to 10 day intervals.
  • or prune the affected areas off the shrub. Dip your cutting instrument in alcohol afterwards and wipe off.
  • or during the winter apply a dormant oil spray to the entire tree or shrub.
  • my least favorite control method may not be available to you depending on pesticide control regulations where you live. A systemic insecticide applied as a soil drench to the root of the tree will help control scale. Applications may have to be repeated yearly. Specific products that are available depend on where you live. I find the products are smelly, require protective gear, are environmentally unfriendly and can stress an already weakened plant.

Edit: Stormy is correct that the white areas on the leaves look like powdery mildew, an airborne fungus. There are a number of control methods.

  • prune the tree or shrub to promote more air circulation.
  • spray with Neem oil or any number of home made recipes such as water and baking soda, dechlorinated water and milk or hydrogen peroxide. None of these home made recipes have worked for me but you may have more success. Repeated sprayings are necessary to continue control.
  • are the terms mealybug and scale insect interchangeable in your part of the world? Just curious... – Bamboo Aug 5 '14 at 10:12
  • Hi Bamboo, no, scale and mealybug are two different species. I take your point though that this could be a white oyster scale. White blobs at a distance could be either. – kevinsky Aug 5 '14 at 11:57
  • My first thought was scale, but to be honest, the States get a lot more types of outdoor mealybug than we do, so I wasn't really questioning your diagnosis, it's just I've noticed on other sites that in the States, scale often seems to be described as 'mealybug' even when its definitely scale, so, as I said, simply curiosity. – Bamboo Aug 5 '14 at 15:15
  • So I added close-ups (as good as I could without a macro lens). The things are tiny and from a google image search it looks more like the oyster scale than the mealybug. – Lodewijk Aug 5 '14 at 19:27
  • 1
    But hey! Those pics of the leaves show POWDERY MILDEW as well...I'd use NEEM at this point (at night just in case the bees are around) to get rid of powdery mildew AND the scale. Need a better, closer view of that bark...IS that the bark of the (Rhododendron, Chamelia...)? – stormy Aug 6 '14 at 2:31

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.