Plant pests, pathogens, and galls, why do we overlook them?
Over the last two years I have become particularly interested in observing plant pests, plant pathogens, and plant galls here in North America. Very often, finding them requires scanning plant life quite carefully as you progress slowly through a landscape.
In general we seem to have the habit of visually ignoring or avoiding looking at damage to plants. There is a sense that this kind of imperfection is "ugly" and unpleasant. There does not seem to be an awareness that damage to plants very often represents the survival work of other organisms, and that those organisms (viruses, bacteria, fungi, arachnids, insects, mollusks) can fairly often be identified to the species level by simply paying attention to the visual characteristics of the damage.
There is a parallel here. I have been interested in seashells since I was a toddler, but for many years I assumed that all the broken shells I saw on the beach were shells which had been whole when the animal died. I assumed that each shell had become broken in the process of being washed up, perhaps by being knocked against rocks, or dashed together with other shells in the waves.
But then I read Geerat Vermeij's 1993 book, "A Natural History of Shells". On page 94 he recounts how, on a beach in Guam in 1970, thanks to a comment from Lucius Eldredge, it dawned on Vermeij that damaged, repaired and broken shells are very often the result of predation. This insight struck him (and, in turn, me) with considerable force.
The damaged plants I see are like the broken shells, not to be avoided with disgust, but to be carefully "read" for the information they contain about the web of life.
Observations
Photos / Sounds
What
Liriomyza eupatoriiObserver
susanhewittDescription
One kind of leafminer on the plant in the previous observation. Hoping to get an ID for the plant...
Photos / Sounds
What
Ash Anthracnose (Plagiostoma fraxini)Observer
susanhewittDescription
Pathogen on Green Ash leaves.
Photos / Sounds
What
Genus ErysipheObserver
susanhewittDescription
Powdery Mildew on Red Clover leaves.
Photos / Sounds
What
Birch Anthracnose (Cryptocline betularum)Observer
susanhewittDescription
On leaves of River Birch. To look at the tree, see the next observation.
Photos / Sounds
What
Cabbage Leafminer (Liriomyza brassicae)Observer
susanhewittDescription
On Garlic Mustard.
Photos / Sounds
What
Liriomyza (Genus Liriomyza)Observer
susanhewittDescription
On leaf of White Snakeroot.
Photos / Sounds
What
Fungi Including Lichens (Kingdom Fungi)Observer
susanhewittDescription
Fungal spot pathogen on Indian Stawberry leaves.
Photos / Sounds
Observer
susanhewittDescription
Feeding marks made by the nymphs of this species on leaves of Chenopodium album, common Lambs Quarters.
I only see this on some very small young Lambs Quarters plants, not on the larger ones.
Photos / Sounds
Observer
susanhewittDescription
Feeding marks made by the nymphs of this species on leaves of young Chenopodium album plants.
Photos / Sounds
What
Nemorimyza posticataObserver
susanhewittDescription
Leafminer in Aster family plant.
Photos / Sounds
What
Ash Anthracnose (Plagiostoma fraxini)Observer
susanhewittDescription
On leaves of Green Ash.
Photos / Sounds
What
Calycomyza promissaObserver
susanhewittDescription
I thought at first this was on a Penstemon plant, but it is in fact a Symphyotrichum sp.
Comments
Thanks for creating this journal entry. It is quite helpful; I'm bookmarking it so that I can refer back to it.
Oh, thanks Suz, I am glad you found it useful. :)
Our problem - in southern Africa - is that most of our galls are unknown and posting galls is a good way to get nowhere. Galls are everywhere, but sometimes one cannot even decide if it is a fungus, mite or insect causitive agent.
The only time that we seem to be able to interest people in leaf-mining and eating insects, is when they are biocontrols (and incidentally identifiable)
The number of Gall projects (https://www.inaturalist.org/search?q=galls&source%5B%5D=projects) is quite impressive.
I've been wanting to post a project on Protea pathogens, but cannot get any experts to buy into the ID, as currently this is commercially handled, and a "free service" might potentially "undermine the viability of the scheme", although in truth, ID to finer levels usually requires microscope work, or culturing, and more recently simple DNA testing. (most of the queries would also be from planted orchards, and iNat handles these identifications rather shabbily, compounded by their being usually being hybrid crosses.).
Thanks for the note Tony. I have now specified that my journal entry is about North America.
We are fortunate in this part of the world because we have Charley Eiseman helping us. Charley Eiseman is the first author, along with Noah Charney, of the 2010 "Tracks & Sign of Insects and other Invertebrates; A Guide to North American Species.
Charley does a lot of research helping discover new leafminer species.
You are right that, without microscope and/or lab work, a lot of pathogens cannot be IDed. And therefore I may be ID-ing quite a few of my pathogen photos incorrectly, because I am not doing the necessary microscopy.
But I will find that out gradually. In the meantime I want to try to make people aware of, and interested in, the organisms that use these commonly overlooked but nonetheless fascinating ecological niches.
I am also trying to get people interested in these in southern Africa. Wont it be great if an iNaturalist enthusiast wrote "our Charney" from material on iNat!
We could try to see if @ceiseman knows anyone in the field who might be prepared to try to help with ID-ing stuff from southern Africa. I imagine that many of the superfamilies / families might be the same, and even getting stuff to that level would be a start.
A million thanks!
I can't guarantee there will be any result at all, but I have asked.
The only lead I have is that Lee Gutteridge has written a guide to invertebrate tracks and signs of southern Africa--scroll down on this page: http://www.natureguidetraining.com/team/lee-gutteridge/
I don't know if he uses iNaturalist, but he may have other suggestions of people to try. His email is here: http://www.natureguidetraining.com/contact-us/
Also, if you have a leaf mine that you know was made by a moth larva, you can search by hostplant in this database: http://www.afromoths.net/
Thanks so much Charley.
@tonyrebelo -- Charley has come up with some promising leads -- see above.
Oh: I am not aware of that guide. Thanks will get it ASAP.
Thanks for Lee's details.
I've been getting into galls a lot recently, too. I'm still floundering, but I'm giving it an effort! Do you note the host plant on your observations? I've found that to be very helpful in trying to ID them. (I use the "Host plant" observation field, but I typically include it in comments too.)
I usually have it the other way - people post the plant and dont mention the galls - have to ask them to duplicate it for the galls. I find it easiest to just add both the plant and gall (when it exists) observations to our "Galls" project.
Often though the plant is not known, so the "Host plant" observation field is useless.
I just use our interactions field ("Parasitizing") which links to the host plant: the ID is there on the linking observation, if and when it is known, and if it changes then it is not incorrectly recorded on the gall observation. (https://www.inaturalist.org/projects/interactions-s-afr)
In the host plant observation field, it is possible to put just the family name, or failing that, just Dicots or Monocots.
The problem is not posting a name, but keeping track of corrections to the ID. Too vague IDs are also not very helpful - but being able to go to the observation for the host and seeing the latest information is quite valuable.
Oh, I was talking about my own observations, not trying to ID others. In most cases I know the plant ID (at least to genus.) If the host plant is unknown, I just remark that in comments. I do try to ID other galls that I have become familiar with, especially when I can also recognize the host plant. Plus, after a bit, you come to know certain galls will only show up on certain plants. Susan, you can put any level of taxon in the host plant field.
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