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By Leah Fronk
Horticulture Educator
Penn State Extension,
Juniata County
Many farmers and gardeners across the Northeast United States are experiencing flooding this summer. After a very dry spring, the rainfall in recent weeks has been welcomed, wished for, and now we wonder "is this too much rain?" In some parts of the Northeast, the answer is "yes – too much rain." Some parts of our county and state have seen localized flooding. It is not as widespread in Pennsylvania as other states such as Vermont where thousands of agricultural acres have been lost to floodwater this summer. On a recent call with other Extension educators working in the Northeast U.S., New York and all New England states reported flooding of agricultural crops, some states more severe than others.
Floodwater is not simply water from a downpour pooling around your plants, or a garden hose you forgot to turn off - this is called ponding or saturated field conditions. Rather, floodwater is defined as water that has come onto your property from runoff of surface waters from rivers, lakes, or streams. Floodwaters carry serious contamination issues. You can imagine when a lake or river floods, there are many places the water encounters before it reaches your property. These contaminants may be raw sewage, raw manure, chemicals from industrial sites, etc. Floodwater also contains microbial contamination: bacteria, viruses, and parasites. Because of the risk of chemical and microbial contaminants, the U.S. Food and Drug Administration (FDA) considers crops where the edible portion has come in contact with flood water to be 'adulterated' and not to be sold for human consumption. If your garden was in contact with floodwater, the safest bet is to discard the plants.
There are some gray areas in determining floodwater contamination which was highlighted in a recent article from the University of Massachusetts (https://ag.umass.edu/vegetable/fact-sheets/flooded-crops-food-safety-crop-loss-issues). For example, crops where the edible portion was above the flood level, such as sweet corn and staked tomatoes may not be considered adulterated. Another situation is a crop in which the edible portion develops after the flood waters recede, such as winter squash. If you are a grower in this situation, please contact me and we can find an answer.
The majority of farmers and gardeners are not dealing with flooded fields, but rather saturated soil and wet field conditions that encourage plant disease and other symptoms. One symptom of too much water and sudden growth is cracking or splitting of plant tissue. It's common to see a tomato splitting around the fruit when rain comes, since the fruit expands rapidly. However, in the last week, I have seen onion bulbs split open and unripe cantaloupe skins crack from the abundance of rain. Excessive water can also cause fruits to lose their flavor especially if they are close to ripening. You may have experienced this with watermelon. The final stage of ripening is when the sugars form, and excessive rain alters the flavor. In both examples, fruit splitting and flavor, the fruits are still edible. In the case of split fruit, be careful to harvest soon after you notice the splitting because the fruit will be quick to rot and susceptible to disease. Speaking of plant disease, rain, high humidity, and warm temperatures are exactly what most plant diseases require. Leaf spotting, crown rot, and wilting can all be caused by this type of weather. It may seem odd that too much rain would cause plants to wilt, but that is exactly what happens when the plumbing of plants gets infected by a plant disease. The disease blocks the water in the soil from entering the plant, and the plant wilts.
When the soil is wet, it is very easily compacted. Try not to work in your garden when the soil is too wet. Compaction is not easily corrected, and a compacted soil will not yield healthy plants. On more than one evening last week, I have had to resist pulling the weeds that have discovered new life from the recent rains. However, I know that compacted soil can be a problem for years to come, and I'll have time soon enough to pull the weeds.