"What's Wrong With My Plant? And How Do I Fix It" Book Review

I was browsing away a rainy afternoon yesterday in Bookshop Santa Cruz, a fine local independent bookseller, and on impulse, I bought What's Wrong With My Plant? And How Do I Fix It" by David Deardorff and Kathryn Wadsworth. I am happy to report that I do not today have buyer's remorse.

Deardorff is a plant pathologist, and Wadsworth is a garden writer and photographer. They work together, presenting workshops and classes about diagnosing and curing plant problems. They blog at http://ddandkw.com/.

The book is attractively presented, well organized, and uses clear visuals and flowcharts to help you quickly zero in on the particular problem you want to solve.

When it comes to solutions, their first line of attack is to resolve the environmental issues that underlie the problem, and then if all else fails, to look for organic remedies.

I decided to analyze the problem I've been having with the black stuff growing on my toyon leaves and berries (as discussed on last month's Plant of the Month post on toyons).

First, they emphasize that even if you have a complex problem, you need to pick one symptom and use the diagnostic flowcharts to arrive at a cause. I chose to focus on the leaves. Here's how it went.

Turn to the chapter about the plant part with the symptom is the starting point, so I turned to Chapter 2, Leaves and Leafy Vegetables.

The first part of this chapter is a section called 'What is a leaf?" and it provides some good basic botany, lightly presented. I have had a basic botany class - but it doesn't hurt to review!

Next I looked at the page listing Categories of Leaf Symptoms. The first one fit my issue: The Whole Leaf is Discolored. Next question:

Is the leaf turning yellow, brown, or white, but not black? (Nope.) OR Is the entire leaf turning black? (Yes!)

Symptoms are illustrated by colored line drawings, and I recognized my leaf condition instantly.

Can you rub off the black revealing green beneath? (YES!) If yes, sooty mold. For solution see page 254; for photo see page 340.

Wow, that was easy and fast! I flipped through some other sections and found them equally clear and easy to use. The choices are are always A or B, and they are very easy to pick between - distinguishing between the effects of too dry versus too salty conditions, for example, which could be tricky.

Then I turned to the photograph of sooty mold. The photographs are all in one section. The picture of sooty mold shows one leaf and a cluster of leaves, isolated against a white background, which again makes it very easy to focus on the issue - my leaves look just like the photo.

The "How Do I Fix It" section on sooty mold tells me that the black coating is a fungus but it isn't a pathogen. It does not cause disease and is not life threatening to the plant, except that it cuts off light, and it is unsightly. Well, that's good to know! My infected toyons do seem pretty healthy - it's just that their fruits are so disappointingly black instead of cheerfully red.

The "How Do I Fix It" section also refers back back to the diagnostic sections - and I notice that there is a diagnosis based on fruits, so I could have started with the blackened berries and arrived at the same diagnosis.

I love good cross-referencing, so the book gets top marks from me on that score. "Only connect," as a favorite author of mine once wrote (E.M. Forster, Howards End). It's a motto that applies in a lot of different situations.

The authors go on to explain that sooty mold is caused by a variety of sap-sucking insects that poop out sticky sweet "honeydew," which the mold feeds on.

OK, so how DO I fix it?
First, always try to change the growing conditions. In this case the advice is (to summarize): Wash off your plants; encourage beneficial organisms; look for ants that might be farming the insects to collect their honeydew - put sticky barriers on the plants to discourage the ants; blast the plants with water spray to wash off the insects; and stop using high-nitrogen fertilizer, which encourages aphids.

Then, if all else fails, try using organic remedies to get rid of the insect infestation. Detailed sections explain the benefits and dangers of organic chemical solutions, as well as how and when to apply them. Three solutions are presented: insecticidal soaps, neem, and pyrethrin, with cross references to help identify the specific insects involved so you can choose the appropriate chemical.

As a wildlife gardener, of course, I don't mind that our native insects dine on my plants and grow their babies there, so long as everything stays more or less in balance. The authors of What's Wrong With My Plant?, however, divide insects into friends and foes, maybe because their book focuses on problem situations in which things are already out of balance. And their insect foes are not all equal: some are presented as being less harmful to the plants than others. If the authors have not yet done so, I would encourage them to read Bringing Nature Home: How Native Plants Sustain Wildlife in Our Gardens by Douglas W. Tallamy. Or at least Town Mouse's fine review of it.

In the whole fix-it section, the item of greatest interest to me, because it uses a local native, is to grow plants whose nectar attracts the beneficial insects that eat aphids and mealybugs. The authors mention dill, fennel, and buckwheat. Yes, I can plant buckwheats for sure, and gladly! Maybe Eriogonum nudum, which grows locally in our neighborhood, though nearer the creek, could be encouraged to take hold on the slope below the toyons. Eriogonum latifolium, coast buckwheat, also grows well here as a garden plant, though it does not occur naturally on our property.

All in all, I can highly recommend this book. It helped me to quickly diagnose a problem, it is very well organized and usable (as a tech writer I do appreciate those points) and I like the authors' approach of addressing the root causes and changing the growing conditions - and then using organic remedies if necessary. And finally, the quality of the information is excellent. It remains to be seen if it will help my toyons, but I'll certainly be giving it my all and will report back on this at berry time next year.

They do not address sudden oak death, however, and I think that is because it doesn't have any handy diagnostic symptoms: when you see the symptoms - it's all over for the oak. Please read Town Mouse's short post for today on the topic of SOD and what you can do to stop its spread.