What's eating my acorn squash?

Acorn squash (Cucurbita pepo) is vulnerable to the same cucurbit pest trio: squash vine borers, squash bugs, and cucumber beetles. As a vining crop that stores into autumn, the fruit is also targeted by groundhogs and deer late in the season. Powdery mildew reduces late-season yield but rarely kills plants before harvest.

Frass at stem base; vines wilt suddenly mid-season despite adequate water; internal caterpillar tunneling collapses vascular tissue. Foil wrap on lower stems; row covers early season; late planting date (early July in northern US) to miss peak borer flight; Bt injection into stems.

Bronze egg clusters on leaf undersides; nymphs and adults suck sap leaving angular yellowed patches; vines die back from the tips. Daily egg-mass scouting and removal; hand-pick adults into soapy water; clean up crop debris promptly after harvest.

Adults chew leaves and flowers; bacterial wilt spreads plant-to-plant via beetle feeding; infected plants collapse within days. Row covers until pollination; kaolin clay spray on foliage; pyrethrin at flowering if beetle pressure is high.

White powdery coating on upper leaf surfaces in late summer; leaves yellow and die early, reducing fruit size and sugars. Plant mildew-tolerant varieties; space plants for airflow; apply potassium bicarbonate or sulfur-based fungicide at first sign; remove badly affected leaves.