swamp milkweed questions
Many leaves on my swamp milkweed plant have had some sort of discoloration much of this year. Is it a fungus, and is it harmful to feed the affected leaves to monarch caterpillars? Also, the plant has been very stalky/leggy/top-heavy this year and I've had a hard time keeping it upright. Any advice on that issue?
The red foliage looks like a stress sign. Perhaps the area gets some shade and is densely planted. It can be normal to lose the lower leaves after the plants reach a certain height. You can always stake the plants if they are falling over.
We do notice some aphids and cast skins on the plant which can stress the plant. Hose off the aphids with a forceful stream of water from the hose.http://extension.umd.edu/hgic/earth-friendly/aphids-got-your-milkweeds
The monarchs should be fine.