Mold remover formula

The Science of Keeping Your Pumpkins Mold Free This Halloween

For many Americans, pumpkins mean fall is here. In anticipation, cafes, restaurants and grocery stores are launching their pumpkin flavor promotions in late August, a month before the official start of fall. And shoppers are starting to buy cool decorative winter produce, such as pumpkins and turban squash, during the hot, sweltering days of late summer.

But those fruits — yes, botanically, pumpkins and squash are fruits — don’t last forever. And they may not even make it to Halloween if you buy and prune them too soon.

As a plant pathologist, gardener, and self-proclaimed pumpkin fanatic, I have both boldly succeeded and failed miserably at growing, properly sculpting, and keeping these iconic winter squashes in their prime until the end of October. Here are some tips that can help your epic sculpt survive Day of the Dead.

This pumpkin carved from a pumpkin with a pre-existing fungal disease, southern blight, shows symptoms of soft rot, especially around the nose and eyes. The round, ball-like structures that form inside the eye socket are mushrooms. Photo by Matt Kasson via The Conversation

Choose a healthy pumpkin and carry it with care

It might seem obvious, but buy a pumpkin the same way you shop in the produce aisle. Whether you plan to prune them or not, choose pumpkins that are not damaged, dented, or diseased. Is the stem loose? Is there a clean break in the crust? Are there water-soaked stains on the exterior?

Post-harvest diseases – those that occur after the pumpkin is removed from the vine – can occur anywhere between the field where they were grown and your front step. A bruise or crack will allow opportunistic fungi, bacteria, water molds and small insects to invade and colonize your pumpkins. Keeping the rind unblemished and the stem intact ensures your precious pumpkin has a longer shelf life.

The return trip also counts. Most of us carry pets, children, muddy hiking boots, and food in our cars, turning our vehicles into giant petri dishes that harbor common environmental molds and bacteria. Some of these microbes could colonize your unsuspecting pumpkins.

Secure your pumpkins on the way to your house so they don’t get bruised or broken stems. My family often uses seat belts to protect ours. Once home, do not carry your pumpkin by the stem, which can lead to breakage, especially if it is large and heavy.

Keep them clean and dry

Pumpkins spend most of their lives in the field, growing in soil teeming with fungi, bacteria, water molds, and soil-dwelling animals like nematodes, insects, and mites. Removing these organisms and any eggs they may have attached to your pumpkin’s rind will help preserve it.

To get rid of them, wipe down your pumpkins, preferably with a bleach wipe or two. This is especially important if you plan to carve them: piercing the dirty bark with a sharp tool will introduce these eager visitors deeper into your pumpkin’s heart. Also be sure to use clean tools. Microbes can reside and multiply on small amounts of pumpkin debris stuck in the tines of dirty carving knives.

Even if you don’t carve your pumpkin, wiping it down isn’t a bad idea, as it may have small bruises or cracks that are easy to ignore.

Carefully hollow out pumpkins, but don’t overdo it

A big part of the job of carving a pumpkin is separating the fibrous strands and seeds inside from the harder pulp that makes up the walls of the pumpkin. When digging the innards of the pumpkin, carefully inspect the interior walls for soft rotten spots or dark tissue, which may have been colonized before or after harvest by bacteria, fungi or water molds. Sick pumpkins sometimes produce an off-putting smell, so use your nose as well.

If you encounter these problems while carving, you can try carving another pumpkin. You can also paint your pumpkins instead of carving them, eliminating the need to look inside.

Two butternut squash halves, one healthy, the other distended and turning gray with a watery pulp

As the soft rot progresses in the diseased squash, the water-soaked appearance expands and the pulp eventually becomes watery like baked pumpkin pie. Photo by Matt Kasson via The Conversation

Some online tutorials and YouTube videos recommend thinning the walls of pumpkins to better allow candles or LED light to pass through. But if you make the walls too thin, the fangs of your jack-o’-lantern will become inward-curving tabs of skin as the pulp dries out and deforms. A toothless pumpkin scares no one.

Another benefit of maintaining thicker walls is that it allows you to experiment with 3D sculpting. It involves shaping the surface of the pumpkin like you would carve a piece of wood, without drilling into the shell, and can produce dramatic results.

Some people soak their carved pumpkins in diluted bleach or vinegar water after finishing them. But this technique is a double-edged sword: adding more free moisture to your masterpiece invites wind-blown mold spores and rain-splattered bacteria to colonize it. However, applying a light coat of petroleum jelly or vegetable oil to any exposed parts can extend the shelf life of your carved gourd.

Protect your creation

October is a wet month with frequent rain in many parts of the United States. Rain falling on your jack-o’-lantern will invite any mold in the neighborhood to take hold. For this reason, I recommend keeping your pumpkins on a covered porch or displaying them indoors in a window.

It’s okay if mold forms indoors, because not all fungi cause soft rot – diseases that produce wet spots that spread, turn mushy, and turn black. If a pumpkin gets too moldy on interior walls, move it outside to avoid producing lots of spores in your home.

When your pumpkin starts to mold and crumble, don’t throw it in a landfill. Take it out for your neighborhood deer or on your compost pile. Or find a spot in your yard where you can watch it decay over time, until it comes back to earth in time for next year’s pumpkin patch.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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