Canna Leaf Problems and Not blooming?
Do Your Cannas Look Like This?
This spring was my first time planting Cannas. I knew they were relatively easy fast growing plants based on some that were planted at my work. All was well for about the first month when all of a sudden, all new growth ceased and the new leaves that were emerging from the center were turning brown/black and not unfurling. I was puzzled to say the least, even more so because I still had some growing just fine in pots away from the main garden plantings. I figured it was the heat and slight drought we experienced in June so I didn’t think much of it. Then, when I planted my healthy ones, they too exhibited the same problems. After doing some quick research, I discovered something called a Canna Leaf roller. So I went out and manually unfurled all the decaying new growth, and sure enough discovered some caterpillar looking things along with dozens of black seed looking things as well as some spider web looking silk. As it turns out, the Cannas were being eaten to death by this pest. There wasn’t a whole lot in terms of specific treatment information for these other than cutting off all the dead and decaying leaves which I did.
The solution, Google Search for organic non invasive treatments! I found something called Bonide Bt. This stuff is a liquid bacteria treatment which spells doom for the dreaded leaf roller. The cool thing is that it specifically targets caterpillar type bugs so it presents no danger to beneficials. Spray this stuff and within 2-3 days, those suckers are history. First, cut the dead and dying foliage, then simply mix Bonide BT per instructions and spray away. Now this stuff is water soluble so you may need to respray if you get rains soon after spraying the first time.
Results were amazing, within 1 week, I had 2 blooming where before there was nothing. The rest had at least 1 healthy leaf showing no signs of the pest. Unfortunately, I treated them a bit late (early July) so I probably wont get a whole lot of growth this year but at least they were saved them from certain death. The good thing is that now I know (as will you!) the signs of this pest so next time around I will treat much earlier.
The strange thing is that I don’t really know where they came from. There aren’t a whole lot of folks growing Cannas in my neighborhood. There are a few a couple blocks down the street but theirs look healthy. So at this point, I have no idea where these things came from since I planted Canna roots with no top growth. The only suspect I have are the 2 Cannas that I bought at Home Depot that must have came with these that quickly spread to the others. I have no idea if these turn into moths/butterflies so I don’t know if that’s how they spread. So if you have Cannas that are suffering from these pests, hurry on out and get that Bonide BT quick because they can do incredible damage in a short period of time! Also, do not leave any affected growth that you may have cut off at the planting site and remove all dead growth in the fall once the plants die back to the ground. Doing this will surely give you healthy Cannas the following year!