Canteloupe Failing to Thrive


Vines have struggled this year. Started slowly, I think due to a cool June in Kitchener area. Some vines shrivelled and died. Wasn’t from lack of water. Didn’t see any striped cucumber beetles this year, which I know do spread disease. Some vines have flowers; may still get some fruit. before frost. What do you think may have gone wrong? Have had success in previous 4 years. I do rotate where I grow them.


I am sorry to hear that your cantaloupe crop has been struggling this season. You may have heard of Vine Decline in melons. In Ontario it can be caused by a soil borne Monosporascus fungus. In early spring it attacks the roots of the plant, slowing growth, and continues to spread through the roots until the plant reaches a point where it can no longer sustain itself, and the foliage rapidly dies off. This usually occurs late in the season.

Diagnosis is confirmed by digging up the roots of the dead plants and locating the tiny black spheres which are the fruiting bodies of the fungus. Has your summer season been hotter than usual in Kitchener? Heat and high moisture can accelerate fungal growth.

Solarization to kill the fungi has been found to be ineffectual. Planting resistant species is recommended as well as cultural practises to encourage strong root growth including: providing a freely draining soil with a high compost content. Melons are heavy feeders, and love full sun. Adding well rotted manure and/or compost to your soil before planting each spring will help provide nutrients. Avoid heavy nitrogen fertilizers during the growing season as they encourage leaf growth instead of flowers. See attached websites for more information on specific cultivation requirements. One particular point of interest is not overwatering your plants once they bear fruit, as you can end up with loss of flavour.

Cantaloupe melons require pollination for fruit to grow, aka fruit set. If you have inadequate pollinators in your vegetable patch you may need to give your plants a hand by pollinating them by hand. Instructions to do so can be found in the first reference.

If you dont find any sign of the Vine Decline fungus it is possible that your cantaloupe melons have been infected by another disease or insect pest. I have added a link to a website that has images of infected cantaloupe plant parts so that you can examine your leaves and stems and diagnose your problem. If you find it difficult to solve, feel free to send us some photos and we can try to work it out. Follow the Plant Identification instructions on the Toronto Master Gardeners/ Ask A Master Gardener website.

Good luck.