Post by incidencematrix on Mar 12, 2014 21:59:08 GMT
Greetings, all. Some elements of my drosera collection have recently been struck by an unusual blight; it doesn't match any known issue that I've been able to discover, and I'm hoping that someone here may have some insight into what might be wrong. Photos are included below; however, let me first describe the context, the symptoms, and factors that have been presumptively ruled out.
Growing context:
Several large trays, primarily containing small pots of drosera seedlings (with some more mature plants, and some non-drosera mixed in). All trays are indoors, in a large window that gets substantial flux. The trays are watered regularly w/ROF water (filters verified periodically by testing TDS). The growing environment has not changed for some months, and the plants generally are/have been quite healthy. No insect or arachnid parasites have been found so far (I have looked); the trays have (deliberately introduced) springtails, which serve to reduce fungus growth and provide food for seedlings but do not eat the plants.
Affected population:
So far, only drosera. More than one species has been affected (capensis and hartmeyerorum for sure, and _possibly_ sessifolia, although that case was more ambiguous). Affected plants do not appear to be clustered by or within tray, and are usually mixed with healthy plants (sometimes in the same pot).
Symptoms:
One or more fronds of the affected plant are or become pale, with tentacles that are underdeveloped or altogether absent. In extreme cases, the leaf surface may be greatly atrophied and the stem may be abnormally curved. The frond surface is otherwise smooth and unblemished, with no evidence of wounding, rot, browning/dessication, etc. The symptoms are generally observed in newly unfolding fronds, which develop abnormally; existing fronds are rarely if ever affected (although it is possible for a frond to become abnormal during its development, in which case the later-unfolding portion will show abnormalities while the earlier portion may be more or less healthy). Note that abnormal fronds can and often do coexist with healthy fronds on the same plant, and (as noted above) abnormal and normal plants can coexist in the same pot.
Factors ruled out:
- Since healthy and sick plants are mixed (across multiple trays), the putative agent is not spatially localized.
- Since the abnormality affects multiple species, it is unlikely to be anything intrinsic (e.g., a developmental issue related to a specific plant lineage).
- Since the growing conditions have been constant for some months, and most plants are healthy, it seems unlikely that there's anything grossly amiss there; likewise, the sick plants are in the same environment as the healthy plants, and (per above) there are no obvious differences in their growing conditions (e.g., they have the same light, water, soil, etc.)
- I have tested the water, and it seems to be fine (low TDS, as expected for ROF).
- The lack of obvious wounding, the developmental nature of the abnormality, and the lack of a visible agent suggests that this is not the work of insect parasites; the symptoms don't seem to match any that I've read about, either.
- Since the plants are indoors, the number of agents that could be acting on the plants is relatively limited. :-)
That's where things stand at present. Has anyone ever seen something like this? I'm including some links to photos below, with abnormalities circled in red. The photos are imperfect, but may provide a somewhat clearer idea of what is going on. I've been growing drosera for a while now, and this is the first time I've run into this....
Thanks!
-Carter
Growing context:
Several large trays, primarily containing small pots of drosera seedlings (with some more mature plants, and some non-drosera mixed in). All trays are indoors, in a large window that gets substantial flux. The trays are watered regularly w/ROF water (filters verified periodically by testing TDS). The growing environment has not changed for some months, and the plants generally are/have been quite healthy. No insect or arachnid parasites have been found so far (I have looked); the trays have (deliberately introduced) springtails, which serve to reduce fungus growth and provide food for seedlings but do not eat the plants.
Affected population:
So far, only drosera. More than one species has been affected (capensis and hartmeyerorum for sure, and _possibly_ sessifolia, although that case was more ambiguous). Affected plants do not appear to be clustered by or within tray, and are usually mixed with healthy plants (sometimes in the same pot).
Symptoms:
One or more fronds of the affected plant are or become pale, with tentacles that are underdeveloped or altogether absent. In extreme cases, the leaf surface may be greatly atrophied and the stem may be abnormally curved. The frond surface is otherwise smooth and unblemished, with no evidence of wounding, rot, browning/dessication, etc. The symptoms are generally observed in newly unfolding fronds, which develop abnormally; existing fronds are rarely if ever affected (although it is possible for a frond to become abnormal during its development, in which case the later-unfolding portion will show abnormalities while the earlier portion may be more or less healthy). Note that abnormal fronds can and often do coexist with healthy fronds on the same plant, and (as noted above) abnormal and normal plants can coexist in the same pot.
Factors ruled out:
- Since healthy and sick plants are mixed (across multiple trays), the putative agent is not spatially localized.
- Since the abnormality affects multiple species, it is unlikely to be anything intrinsic (e.g., a developmental issue related to a specific plant lineage).
- Since the growing conditions have been constant for some months, and most plants are healthy, it seems unlikely that there's anything grossly amiss there; likewise, the sick plants are in the same environment as the healthy plants, and (per above) there are no obvious differences in their growing conditions (e.g., they have the same light, water, soil, etc.)
- I have tested the water, and it seems to be fine (low TDS, as expected for ROF).
- The lack of obvious wounding, the developmental nature of the abnormality, and the lack of a visible agent suggests that this is not the work of insect parasites; the symptoms don't seem to match any that I've read about, either.
- Since the plants are indoors, the number of agents that could be acting on the plants is relatively limited. :-)
That's where things stand at present. Has anyone ever seen something like this? I'm including some links to photos below, with abnormalities circled in red. The photos are imperfect, but may provide a somewhat clearer idea of what is going on. I've been growing drosera for a while now, and this is the first time I've run into this....
Thanks!
-Carter