I planted cucumbers (straight eights) from seed in mid-April here in inland So. Cal. Growth rate was great until early June. New leaf growth was stunted and mature leaves developed light brown patches. Some mature leaves then turned dark green with a sticky film and curled edges. No notice of any white or gray powdery residue. Plants then stopped growing and had to be removed. I'm growing other Cucurbits like winter squash with no problems. Any ideas?