How to Prepare and Submit Data for Plant Diagnosis

September 23, 2010

For insect and disease diagnosis, yesterday’s article mentioned two referrals:  California Pest Prevention Services and your local Master Gardeners Association. It’s important that you give as much information as possible when seeking their assistance. Below is an overview of what type of questions you can expect to answer.

The current form at the California Pest Prevention Services office asks for the following information:

  • Plant distribution (limited, scattered or widespread)
  • Plant parts affected, such as bark blossoms, seeds, tubers, etc. (seventeen choices given)
  • Plant symptoms 

Basic questions your local Master Gardeners may ask.

  • Description of problem
  • Name of problematic plant/tree*
  • Watering method (how frequent and duration)
  • Location (north, south, east, west)
  • Applications of fertilizer, pesticides, amendments, etc.
  • A description of the surrounding area of the plant/tree, i.e. neighboring vegetation, slopes, animals, drainage.

Further information that Master Gardeners may need could include, but are not limited to the following:

  • Perennial, evergreen, annual or deciduous
  • Age of plant/tree
  • Number of plants affected with same problem
  • Planted in the ground or a container (what type of container and duration)
  • Sun/shade exposure (how many hours, morning or afternoon)

Of course, both organizations will need your name, location, and county. The environment, conditions, and care involving a plant are important factors in diagnosing a problem. So be ready to give as much information as possible.

As stated below, provide a good sample. The sample should be fresh, placed between two sheets of newspaper or paper towels in a baggie.


*If you don’t know the name, they can help identify the plant. Provide a good sample (leaf, stem, and flower) and a photo of the plant/tree.






  1. I sure hope all my growing things remain healthy!! That sounds like a real job filling out all that information. I can understand why they need all those details to make a correct diagnosis. Sounds very thorough.

    I sometimes have taken my questions to my local nurseryman. He has been quite helpful, but it is good to know that there are at least a couple of other sources where one can get answers. Thanks.


    • It isn’t always necessary to provide all of those details. Many times, these professionals know what the problem is immediately. I’ve used reputable nurseries as well. Once, though, a “reputable” nurseryperson told me that the library has a Sunset Western Garden Book where I can look it up. Other times I get a generic answer, and that may be all I need or want—quick and easy. However, all those details usual leave the gardener more educated.


  2. The detail information is also useful when talking with your local growers at farmer’s market. I find that I get more useful information from them while shopping for local produce. They generally come across the same pests as we do and know immediately what is causing the damage. In my town growers from different regions (central or coastal) come on different days, so I try to get different opinions. I buy specialize produce from them while gleaning valuable growing information.


  3. If sending a digital picture to someone for plant identification: include at least 3 pictures, a closeup of a leaf (both front and back), a closeup of the bark of the trunk (an important identifier), and a long shot of the entire plant. And because many of us have slow Internet speeds, send the pictures on the small or medium setting, not large. Try to keep the entire email under 1.5 mb.


    • Good suggestions on the three photos, and settings when sending via email. I should have thought of this as I have dial-up. Thank you, Farmer Fred, and everyone for your input.


  4. Self diagnosis. I bought a bamboo plant at the Galt Flea Market yesterday and diagnosed it today as ‘the cat bit off all the leaves!’ Generally, though I have an instinct about what is wrong and try a few different things, like move the plant to another location or put some snail bait out or wash the leaves off. most time the intitution works for me.


  5. Tonight is our first official meeting as cactus club members. We are looking forward to the ‘country store’ and brining home lots of ‘good stuff’.


  6. I sure wish that I could grow cactus. I know what I do wrong. I give them too much water. My mother-in-law grew beautiful tall, or big and round cactus. They have the most beautiful blooms. I have given up on cactus but sure enjoy seeing the flowers on other people’s plants.


  7. I know how Valerie feels about growing cactus. I gave up long ago on growing regular cactus and now only grow Christmas cactus. I still have problems with keeping the buds from falling off. It’s either too much water or watering at the wrong time. I can get the cactus to bud but can’t get it to bloom as the buds fall off before blooming. Does anyone know the proper timing of watering? Do you stop watering when the buds set? I sure would like to see some “pretty” flowers for Christmas instead of sweeping up the fallen buds.


  8. Betty, I am with you. I will stick to Christmas cactus too. I have the best luck with growing it indoors. It sometimes has gotten pretty dry before I water it. You can kind of look at the plant and see if it looks a little sad or not and usually then I would water it for sure.
    Outdoors on the shady side of the house I had one growing and I would water my plants in the pots located there with the hose and I think I would give it too much water and some of it would just break off at soil level. I think it was rotting it. I have mine removed into the garage right now by the window. What I really should do is buy a whole new, very healthy plant and start fresh.


  9. Hi everyone, found these comments regarding cactus. I learned last night at the meeting that cactus need to be watered preferably from the bottom up or around the base of the plant. One of the members said if the water gets on the top of the cactus it hurts the plant. I, of course, had been watering with a hose on the top of the plants.

    They tell me water once every two weeks. I have always watered too much too. I am trying to cut back on the watering.

    I brought home 2 Christmas cactus from the raffle (small starter plants) that I will have to pot myself. We will see where that goes.

    Most of my plants are small, except for the Aloe veras. Some years ago I did have a couple of large plants approx. 4-5 ft. tall, but they died.

    I still suspect ‘over watering’ is the problem.


  10. Betty, I never had any problem with the flower buds falling off my Christmas cactus, only if I accidently hit one with my hand or watering can, I maybe watered it once every week or week and a half. I would take it to the sink and let the water run out of the bottom. Let it sit for a while and then put it in its saucer. I had it by a window facing west. I probably repotted it at least two times as it grew and put it in bigger pots. It would usually bloom by Thanksgiving. It is possible that sometimes it wouldn’t get water for two weeks, but if I looked at it, I could tell it wanted water. I don’t know if your bud drop is due to watering habits, maybe Farmer Fred will let us know.


  11. Bernadine, Sounds like you are learning a lot about cactus. Aren’t you glad you learned not to water them with the hose? Cactus is definitely a difficult plant for us who are so protective of our plants and think they need a drink of water when they actually don’t. Plants do need the oxygen and if they are all soggy they won’t be getting it. Good luck with your cactus. Hope you get some beautiful blooms.


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