What's your question? Ask

See the link at the end for common pests of cup plant. Many are native insects and an important part of the ecosystem. Did you know that most birds feed their nestlings insects, even the birds that come to our feeders? Another cause is sometimes called senescence; the lower leaves get old and become shaded out by upper leaves. They may yellow, shrivel and die. Check for pests but this may be natural on this plant. Have you grown sunflowers: they do the same thing. I remove leaves that are not mostly green to reduce the risk of disease and to make the plant more eye appealing. The fact that your plants go on to bloom well indicates that this isn't a serious problem; instead, it is more of a nuisance. https://www.canr.msu.edu/nativeplants/uploads/files/Cup_plant.pdf