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Question
I've had a tibouchina for more than 10 years. It has been thriving, Needing only some occasional pruning. I recently brought in a lot of new redwood mulch and redesigned the garden. Suddenly the large shrub is infested with red spider mites. This has never happened before. They have infested my whole yard but this plant seems to be suffering the worst. I have applied weekly applications of Neem oil (twice) which has seemed to help. Now I have leaves with holes in them, so there is something else going on. And also possibly white flies. Also daily there are more and more yellow/orange leaves. I am suspecting the plant is now stressed and more vulnerable. How do I break the cycle? Should I keep up with the weekly neem oil spray?  Or now that the worst of the infestation of red mites has passed, should I get some ladybugs?  Perhaps also a very deep slow watering?  I've never had trouble with gardening in the past or with this plant in particular.  I'm having so much trouble after redesigning the garden and bringing in new mulch and plants.

My geranium leaves up on the balcony are all turning yellow. The leaves look like they have specks of I dirt in them and I cannot tell if it is dirt from the hand watering spraying onto the leaves or insects causing the leaves to yellow. I've never had these types of problems before and since I just spent a lot of money on  new landscaping I'm quite distraught!  The squirrels are eating all my flowers (lobelia, and many others) the red spider mites are on every plant in the garden (I've completely lost a new Petite Butterfly Bush). The mites have even travelled up to my balcony container plants. Is there a chance they came in with the mulch?  Any advice you can provide would be so helpful to me.  Also, I wasn't done with purchasing and planting additional plants. How long should I wait to do that?
Thank you,
Sherril hopper
PS. If it matters I live in Zone 8, which is near San Jose , CA

Answer
Sherril:

Spider mites can be a real pain. They tend to be worse during hot dry weather and mostly feed on the lower leaf surfaces.  They have 8 legs and are not true insects, but rather related to spiders and scorpions. Between the mulch or plants being the source, I would come near leaning toward other plants.  Although they cannot fly, they can travel on wind and splashing water.  These critters are hard to deal with.  At one time there was a product (insecticide) called Kelthane that was quite effective and was labelled for many plants.  You may still be able to find it at an obscure nursery or garden center.  If you find it, be sure it is safe for your plants before using and follow the application instructions.  Insecticidal soap does have some limited effectiveness as does spraying the leaves with a strong stream of water to wash the mites off.

Not sure about the geranium leaves.  Sending a photo may be useful if you can.

Regards
Steve

Plant Diseases

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Dr Stephen Vann

Expertise

Plant Diseases and Disorders of Lawn Grasses, Trees, Vegetables,and Ornamentals

Experience

Plant Diseases Identification and Management

Education/Credentials
B.S. Botany --- Miss. State Univ. M.S. Plant Pathology --- Miss. State Univ. Ph.D. Plant Pathology --- Texas A & M Univ.

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