Hello, I am growing three buttercup squash (Cucurbita maxima) plants in my home garden located in Blaine, MN. The season started great and vines grew quickly and had three female flowers successfully pollinated in late June and first couple days of July. The fruit developed quickly and are still doing well. Since that time I have had only two female flowers open, neither set fruit despite hand pollination efforts. In the last two weeks zero female flowers have opened. The plants are producing many female flower buds but they all turn yellow and die before opening at varying stages (photo attached). The plants look healthy and male flowers have opened regularly. The plants receive regular watering from drip irrigation. The only chemical applied was a dose of permethrin due to presence of squash vine borer eggs. Permethrin was applied according to label instructions several weeks ago. Wondering what could be causing all three plants to abort the female flowers? Could the permethrin have stressed the plants? Could the weather simply be too hot this year? Is there anything I can do to encourage female flowers to open for a chance at pollination and increased yield? Thanks! Brad