I have had several watermelon plants and they all seem to be growing well; we get lots of little baby watermelons to start but before they can get bigger than about the size of a large pea, they shrivel up and turn black. It’s really very upsetting and I don’t know what to do. I was thinking there is a nutrient deficiency, although we did get food for them, or maybe some type of bug or something?
The Gardener’s Answer
Hello, Rachel in Hawaii: Watermelon are susceptible to several different diseases. Without seeing your fruit I cannot say for sure. What does the foliage on your vine look like? Is it healthy or is it also struggling? It is not likely a nutrient deficiency or even an insect problem, but more likely a fungus/pathogen issue. Have you grown other members of the cucurbit family in this space in the past? This would include cucumber, pumpkin, cantaloupe, and squash, and if so did you have problems with these crops? In terms of failure for this year’s crop, possibilities include blossom end rot, anthracnose, mosaic virus, and bacterial wilt. With most of these we would first notice issues on the foliage and then on the fruit. It could also be a pollination problem. The best thing to do would be to take a sample to your Cooperative Extension office and have them send it off for analysis. It does not look like your Extension office has a horticulture/agriculture agent on staff, but they do have a master gardener program, so hopefully someone there can help you or they can send it off to the University to get a positive diagnosis for you. You can visit their Web site at www.ctahr.hawaii.edu/Site/ExtPrograms.aspx
. The only way to prevent future problems is to find out exactly what the issue is. You will want to pull all diseased plant material from the ground and turn the soil so the potential for disease does not survive from year to year.