Garden Pests and Diseases: Colocasia: Water soaked spots, orange spots, & black bugs, 4 by SavvyDaze

SavvyDaze wrote:
I have several Colocasia Black Beauty pups I brought inside for the winter. (However, our winter has been so mild that I could have left them outside). Anyway, they have been growing really good in my bathroom which gets good sun for about 3 hours in the early part of the day. I also run a humidifier in there for several hours a day a few days a week. The soil is moist, but not soaked.

So I have 4 problems I need help with:

1) (Pics 1 & 2) About a week ago, I noticed one of my Colocasia Black Beauty was getting some soft, almost water soaked looking spots on, the edges of a leaf, but otherwise appeared healthy and was growing great and putting out a new leaf about once every 2 weeks. These areas are becoming transparent, though. All the research I found with this description mentioned Leaf Blight, but none of the pictures looked anything like the issue with my Colocasia.

2) (Pic 3) Then I noticed that another one of my Black Beauty was developing some orange-brownish areas on the edges of its leaves. When I researched the potential cause for this, one website mentioned the spots could be due to lack of Phosphorus. Because the plants were babies (4-5 inches tall) when I potted them up, I hadn't yet fertilized them. So, I thought, ok, maybe that is the problem, but I do not know for sure.

3) (Pic 4) I also have a Colocasia Fontanessii that has been growing in a pot since July. I received it from the local garden center when they were cutting the pups off their mother plant by their pond. It took awhile, but it is looking good and now about 3 feet tall with 3 leaves and another one on the way. All is well, except for some brown leaf tips. I can not find a cause for this as it is supplied good humidity and water. Thoughts?

4) Ok, so I am an avid plant pest hunter and inspector...inspecting the plants all over...sometimes as much as 3 times a day LOL Yeah, I'm paranoid. However, it paid off. A few days ago, during an inspection, I noticed minuscule black dots, or perhaps they are brown, on the under side of the leaves on just about all of my Colocasia. These dots are the size of a period (.) or perhaps even a little smaller, however, because I inspect so much, I know these dots don't belong there. So, I gentle brushed one onto my finger, pressed against it with my thumb, and a little bit of liquid came out of it. So, I knew it was a pest and not a dust particle or dirt. There were only about 3 to 6 of these bugs on the underside of the leaves. Some leaves only had one or two. The bugs are easy to wipe off or spray off with the shower head, both of which I did to all of my plants. Later that night, after the leaves had dried, I inspected for the black dots and found none. 2 days later, I started finding them again, 2 or 3 on some, not all, of my plants' leaves.

Now I have seen aphids before on my Hibiscus this past summer and these looking nothing like them. There is NO webbing anywhere on my Colocasia...not at the base of the stems, not along the stems, nor under the leaves. But other than these 2 pests, I don't know what else it would be. These black dots weren't seen in the same area of a leaf, but more like one near the tip, another near the bottom, and 1 or 2 around the center. They didn't appear to be moving to the naked eye...just kind of there like a speck of black dust, except they ooze when you squish them. I don't have a picture of them as I wiped down each leaf and sprayed horticulture oil this morning. I think they'd be too small to show up in a picture anyway.

Hope someone here can help me with these issues.

Thanks!