loads of garden trouble

Asked May 7, 2016, 5:41 PM EDT

I have a lemon tree, star jasmine, passion fruit, kangaroo paw, gardenia, bay tree all having a problem, and I'm not sure if its the same problem? I see new shoots and end of leaf tips shriveling and dying. Deformed leafs; bulbous and knotted. Yellowing and browning of leaves. I have examined for pests, but can't see much. I do see webbing, but not sure if its actual spiders or mites. I see small white flecks (could be a kind of white fly, but not the same as the Hibiscus is prone to). Any suggestions?

Los Angeles County California horticulture

3 Responses

With so many different and unrelated plants showing the same symptoms, namely shriveling/dying shoots & tips, deformed leaves, and yellowing/browning leaves - all this points mainly to chemical toxicity. While insects and diseases are selective in their ability to infest or infect plants, herbicide toxicity is "across the board." The symptoms you've described sounds like herbicide damage that may have started 4-6 weeks ago.

Questions: 1) have you used a broadleaf weed killer in and around these plants; 2) have you used a weed & feed turf product in your lawn that may have gotten into the root system of these plants; and 3) have you sprayed these plants with an insecticide or liquid fertilizer that may have been applied with a sprayer that held broadleaf weed killers and was not cleaned properly.

Unfortunately, if the culprit is herbicide-related, not much can be done. If herbicide injury is suspected Do Not Apply a fertilizer. A fertilizer will cause a boost in growth, and a boost in more herbicide uptake which will cause more damage. Irrigation water or rainfall may help greatly to dilute the herbicide product providing the area where these plants are located is not on a down-slope where runoff water may bring in more herbicide.

Good luck! Hope this information is of some use. Feel free to respond.

Hi Vincent. I have not used any weed killers of any kind. I do not have a lawn. I am an organic gardener...... I know the Gardenia has white fly, but its pretty well controlled. I dont know whats making the leaves curl.... The jasmine has a completely different problem, whole new shoots, and leafs browning on end points, then killing the whole leaf..I have seen a similar result on tomatoes before, and I suspect the lemon tree to have the same thing.... I live in Malibu, and on my walks see a lot of other plants in the neighborhood suffering from the same thing... I am at a loss as to how to help my plants.........

Interesting! Well the next best answer is high soil salinity (salt levels). Salts (sodium, chlorine, fluorine, etc) are considered salts and cause very similar symptoms as herbicide injury.

Since your plants show similar symptoms, I would doubt the problem is disease related.

Sucking insects such as aphids, spider mites, scale, mealy bugs, etc. do release toxins in addition to killing individual plant cells that result in cupping, twisting, and yellowing of the affected leaves. But, even insects will not share the host of plant types you've mentioned. However, it is common (for example) that different aphids infest different plants in the same landscape when environmental conditions are just right and at the same time.

Getting back to the soil issue - I would call your local county agent for a soil test bag and form, and have the soil tested for nutrient deficiencies and toxicities (cost ~$20). Since most all plants are showing the same general symptoms I would take 2 or 3 samples of soil from around each plant type and mix them together for one composite sample to send in for analysis.

Pay close attention to soil pH, soil salinity levels (sodium, chlorine, boron, magnesium), buffering capacity of the soil and the levels of micro-nutrients. Here is a link to a good publication: http://www.salinitymanagement.org/Salinity%20Brochure.pdf .

When you receive your soil test results, it should be self-explanatory. But, if you need help your local agent should be able to assist you. And, here is a great publication that will help you understand what you are dealing with: http://www.spectrumanalytic.com/support/library/pdf/guide_to_interpreting_irrigation_water_analysis.pdf

One more thing- the irrigation water! Just as in the case of soil salinity and nutrient toxicity, the same holds true for your irrigation water. Your local water utility district should be running routine analysis on the water they provide. Ask for a copy and compare pH levels and salt level with that of the soil test results. If you are unsuccessful in obtaining a copy of the water test results, then talk to your county agent for a water test form and pay the fee (~$20) to have it tested yourself.

Good luck with all of this.