PPDL Picture of the Week

November 5, 2019

Gourd Pointillism

Dan Egel, Clinical Engagement Associate Professor-SWPAC, Botany and Plant Pathology, Purdue University

This is the time of year when many people start to think about getting rid of gourds and pumpkins in fall decorations. The display in figure 1 has a gourd with some discoloration. The areas of discoloration might be an indication that the gourd needs to be thrown out. In fact, the gourd will continue to deteriorate and rot if left outside.

 

Take a moment to look a bit more closely at the patterns on the rind of the gourd in figure 1. The pattern, in a rough circle, is made up of tiny dots (figure 2). The pattern is caused by a disease known as anthracnose. Anthracnose is caused by a fungus. Before you throw the gourd on the compost pile, take time to look at the lesions, some of which appear to be almost a pointillism masterpiece.

 

Another option to tossing the gourd out is to let it sit for a few months in a dry place. When the gourd dries, the lesion growth should slow or stop. After a few months, you should be able to hear the seeds inside the gourd when you shake it. Add a coat of varnish if you wish. This should preserve the gourd and the natural art work for some time. Figure 3 shows such a gourd on a shelf in the author’s office. Whether you decide to preserve the gourd or just look it over, now you know more about the pretty pattern that nature left on your front stoop.

​Click image to enlarge

Figure 1: A holiday decoration with a gourd on the right with several dark, patterned lesions.

Figure 2: A closeup of the one of the anthracnose lesions on the gourd.


Figure 3: A dried and varnished gourd as a decoration on a shelf.