Disease Control For Microgreens

by Lettuce Be | Last Updated: 07/11/2021

Oh my – mold, fungus, and viruses!

You may expose yourself to one or possibly all of these pathogens, depending on the quality of your growing environment. When you are confronted with them, what are your options?

How do you handle raw foods that have a small amount of mold on them, for instance? Is the whole tray scrapped, or can you harvest the unaffected portion? Pregnant women, newborns, seniors, and those with weakened immune systems can be seriously affected.

You’ve likely experienced the same or similar situations with your products if you grow varieties of microgreens, leafy vegetables, edible flowers, or other edible plants.

disease control of microgreens“Black mold has infected my pea shoots. There are little brown spots on my radish sprouts. What should I do?”

Pea shoots are prone to this problem if you grow them. The black seeds will immediately appear once you open the tray. As a result, it will no longer spread. A fungus is causing this issue. Airflow is the key to fungus.

Consider your growing environment when managing airflow. What is the distance between your trays? What type of growth chamber do you use? How humid is that environment, and does any air move around there? For example, 80-85% is probably too high. Traditionally, peas are a cool-weather crop – is it too warm now? The fungus may be introduced via the seed itself. Sanitizing is vital to avoid the spread of the fungus.

Disease Prevention

Several important factors are to consider when trying to identify the risk of disease in your microgreen system.

How does seeding density affect disease?

Since the trays are stacked, the density of seeds shouldn’t affect airflow. Space out seeds during summer, or in warmer climates, since the seeds are a food source for pathogens, and if they are touching, microbial growth can spread.

Sources of Pathogens

Do fungi in pea seeds come from the environment, or are they more likely to come from seeds?

Peas are soaked overnight, which may provide some pathogens, or at the very least, give them a good start. Next, however, we soak them in a sanitizer that may alleviate this problem. Thus, to control pathogen growth in our environment, we mainly use sanitation.

Studies that demonstrate that hydroponic systems are vulnerable to pathogen proliferation when seeds are contaminated have highlighted the importance of seed sanitation.

Methods of Sanitation

The cultivation of baby greens is always done in closed systems, which makes pathogens inevitable. Include the following items in your routine:

Take these problems as an opportunity to become a better grower. You can avoid future problems by learning what caused them. For instance, we added more compost to our potting soil mix at one time. A flare-up of the disease resulted from this. As we went backward in our chain of events, we could get rid of the disease by only using our layer of soil. Unless you intend to use paper towels, keep them moist, and you can easily remove them.

It’s Not Always A Failure

It is possible to save a tray of seedlings with a disease by taking the time to plant them. There’s no doubt you invested a lot into that tray, so at least you could cut off the healthy portions and still sell it. In addition, you can often remove diseases affecting mature plants at the base by cutting above that point.

Management of Viruses

Especially since the brown spots on the true leaves (not the mature leaves) of radishes appear in the late stages of the crop’s development, a virus likely causes them. Unfortunately, you can’t treat viruses with sanitization or antibiotics. To prevent their spread, you should control the environment.

Management of Seeds

Learn about your seed company. Pathogens like E.coli, salmonella and listeria monocytogenes should be tested on the seed. In light of the experience you’ve been having with this seed, what are other growers reporting about it? You must test your system’s ability to germinate conventional seed options before you purchase many seeds.

Regulations on Microgreens

U.S. FDA regulates products in the U.S. As a distinct commodity, microgreen species are considered covered produce under the food safety modernization act and are not considered sprouts under the legislation. However, recent outbreaks have revealed pathogens that might change these regulations. Safety should always be the top priority.

Sanitizing Agents

Sterilizing is different from sanitizing. Sterilizing is only done in an autoclave to kill both live and dead pathogens. Sanitizing in microgreen systems only kills living pathogens, but not dormant pathogens that can later break dormancy.

Improving Your Approach

You may need to spray your system with a sterilizing agent more frequently if there is an outbreak, for example, but it isn’t a requirement. In contrast to some systems, we do not spray sanitizing agents on our shoots after they sprout. It may be necessary to implement steps like this in your system, but it should be based on observation.

In most cases, contamination comes from the seed. Even though we soak larger seeds in a sanitizing agent, we do not soak tiny seeds like broccoli microgreens since they cannot quickly absorb water. Instead, after they have been spread, you can spray them with hydrogen peroxide. This means that not every surface needs to be disinfected.

As the reach of these delicate greens expands, accountability and traceability become more vital. Will it be shipped between states? It would help if you took more precautions as your reach increases.


If you’ve grown delicate greens or vegetable greens, this article covers a lot of essential details. In addition to preventing foodborne illnesses, sanitization will prevent significant yield losses. One of the keys to becoming a great grower is effective disease prevention and treatment, often overlooked. We are still at the beginning of discovering preventive treatments and interventions that will help maintain the nutritional quality and safety of microgreens.


What are the benefits of eating microgreens?

Health-conscious consumers and restaurant chefs are drawn to these tiny leafy greens because of their health benefits. They contain carotenoids, high nutrient levels, beneficial plant compounds, and bioactive components. Compared to cups of vegetables or mature greens,  the carotenoid concentrations and nutrient content of microgreens are higher which can aid in the prevention of some chronic diseases along with a low-fat diet.

Take leafy greens for an energy boost to slow the aging process, enhance immune systems and enhance your lifestyle.

What are the potential opportunities?

Because of the short shelf life of microgreens, they’re typically not grown on a large scale and shipped for miles and miles like vegetable greens but rather sold directly to local markets, presenting an opportunity for smaller growers.

What are the most severe threats to microgreens?

The most severe threat to microgreen species appears to be Pythium and Phytophthora.

What are the best practices for preventing disease?

The best practices growers can take to prevent disease are to pay close attention to temperature, humidity, growing medium selection, and spacing.

What varieties of microgreens are most susceptible to disease?

The varieties that come to mind based on experience are watercress, Swiss chard, Thai basil, mint, and nasturtium.

What are the risks of food poisoning?

Raw foods that grow bacteria more easily and quickly than other foods are at higher risk and are referred to by the FDA Food Code as “Time/Temperature Control for Safety food” or “TCS food” – (formerly called “potentially hazardous food” (PHF)).

What are the potential causes of sprout-related illness outbreaks?

Salmonella and Escherichia coli O157: H7 have been the major causes of sprout-associated illness outbreaks. But unlike the shoots, buckwheat microgreens contain only trace quantities of fagopyrin and don’t pose a major health risk.