Managing pests and diseases is crucial to the success of your market gardening operation.

No one wants to buy radishes with wormholes or tomatoes with black rings around them, no matter how organic they are.

In this article, we will be taking a look at J.M. Fortier’s methods of insect pests and disease prevention from his book, the market gardener.


The first line of defense against pests and disease is biodiversity. The presence of diverse plants, insects, birds, and amphibians living together on the same site minimizes opportunities for pests to get out of control.

The best way to encourage biodiversity is to provide appropriate habitats for species that you wish to promote.

Windbreaks or ponds work well, as well as shrubs and other plants that attract insectivorous birds.

Floral spaces created inside and along the outer edges of the gardens can be designed to encourage insect predators. Stone walls, trees, and other small refuges can encourage other beneficial insects. 

J.M. has worked for many years implementing steps toward a more biodiverse farm, including:

  • Having a local beekeeper’s beehive on the edge of the garden, which brings more pollinators to his farm.
  • A pond for frogs, insects, and birds of all kinds. The pond is in close proximity to the woods at the edge of his farm, so it is beneficial to the toads that patrol his gardens at night to feast on cutworms.
  • Birdhouses to encourage bluebirds and wrens – important predators that hunt for insects in the soil.

By routinely adding different ecological niches that benefit multiple species, J.M. and team have managed to transform their market garden into a welcoming space for a wide variety of animal and plant species.

In most cases, all they had to do was integrate habitats into the garden landscape.

You and I can do this too!

Establishing a biodiverse market farm is a great first step in combating pests and disease, but unfortunately, it is not the end-all to be all. 

Chances are, pests will slip in there now and again to take a bite or two out of the veggies you worked hard to grow. 

Always be vigilant and on the lookout for pests on your plants, especially if you are newbies like us and don’t have specific insect management practices in place just yet.



Almost all the pest management practices used in organic plant protection are preventative. This means they help avoid pest proliferation but can’t do much when a situation gets out of hand.

Correctly diagnosing common pests and diseases is important. This is the purpose of scouting, which involves observing crops daily and taking note of how potential risks might be developing.

A good habit to get into is walking your gardens every morning before starting work. It allows you to monitor crops for any signs of damage from pests or diseases, and assess all the maintenance work that needs to be done in the garden.

In addition, you can make out an action list of things to do that day. Keeping a daily to-do list is the first step in keeping your market garden under control.

It helps to know what you are looking for as well. If you are a new market farmer (like us) you may not know all the pests that are out there just waiting for you to let your guard down and go to town on the veggies you worked oh so hard to grow. 

Fortunately, there is an email alert service (FREE!) that tells you which pests and diseases to look out for, based on your region.

We just subscribed to this service right now, so I can’t tell you how it has helped thus far, but J.M. subscribes to it, and if it is good enough for him, it’s good enough for us!

Disease Prevention

A stretch of overcast, rainy weather for several weeks is a sign that garden diseases are likely to run wild.

The Solanaceae and Curcurbitaceae families are especially susceptible to infectious pathogens. Other crops can suffer as well, including onions, beans, and greens.

Depending on the strain of the infection, plant diseases can lead to dysfunctions and eventual crop loss. 

When a vegetable disease is detected, the first step is to identify the pathogen in question.

In most cases, the crop leaves will show some kind of symptom (blotches, wilting, burning, yellowing, etc.) which you can compare with a guide to help identify the culprit.

This is not always easy as a plant could have multiple diseases at the same time and symptoms are easily confused with physiological problems (moisture stress, deficiencies, etc.).

Your email alert is especially useful here as it is up to date with current weather conditions, unlike a reference book.

There are three main culprits of vegetable disease: viruses, bacteria, and fungi.

Viral Diseases

These are the least common types of diseases. Most viral diseases spread via seeds, so it’s important to use high-quality seeds.

Garlic seed is particularly at risk, as are tomato transplants from commercial greenhouses.

Bacterial Diseases

These can be severe and require rapid intervention. They usually manifest in rainy weather.

Getting rid of the disease involves removing sick plants from the soil, taking special care that they do not touch any other plants in the process.

It’s good practice to throw diseased plants in the garbage and change your clothes after working with them.

One of the symptoms of bacterial disease is rot, which quickly causes the crop to wilt.

Fungal Diseases

These are pretty common. To help avoid fungal disease, precaution must be taken to avoid damaging plant tissue at all times – from weeding to staking to harvesting – as fungi require a point of entry into the plant.

When pruning, it’s important to work on a sunny day, as water in an open wound creates a perfect setup for the appearance of diseases such as blight.

If fungal disease is detected, the best thing to do to contain the damage is by making weekly sprays of copper and sulfur in alterations.

These sprays are not curative but do allow the plants to continue growing if applied in a timely fashion.

These treatments are effective, but there are some drawbacks:

  • Copper can accumulate in the soil and inhibit biological activity.
  • Sulfur is harmful to garden insects

For these reasons, J.M. and team are exploring different biological fungicides that introduce bacteria to fight certain pathogenic fungi.

They are also looking into inoculating the beds of susceptible crops with beneficial microbes that will protect plants from soil-born pathogens. 

Both of these practices supplement rather than harm biological life in the soil.

Another preventative measure is to pay close attention to what the seed catalogs have to say about different cultivars. Some are resistant to diseases. These seeds are more expensive, but often stop the problem at the source.

Relying on resistance in varieties is especially important when it comes to growing in greenhouses and hoophouses.

In these moist environments, tomatoes and cucumbers are not rotated and are highly susceptible to annual contamination.



Insecticides are a last resort when battling pests. Using insecticides are not ideal, let’s just say that.

However, if the choice is between using biopesticides and losing an entire crop, choosing to use biopesticides is something to seriously consider.

The ‘bio’ in front of ‘pesticide’ indicates that these products are natural in origin (not chemically derived), break down over time, and do not pollute the soil with toxic residue.

Biopesticides may be:

  • Persistent: active for several days
  • Selective: intended to attack a specific host
  • Broad-spectrum: active on a number of insects

In all cases, they are toxic and should never be viewed as harmless substances just because they are allowed in organic agriculture.

Keep in mind that these biopesticides are made by the same multinational companies that manufacture and promote synthetic pesticides that damage human health and the environment.

If you choose to use biopesticides, take the same precautions as synthetic pesticides and wear protective clothing (gloves, goggles, etc.). 

It’s also a good idea to make a chart detailing the proper dosage calculations for each product, along with a reminder of the recommended amounts of time between sprayings.

Bottom Line

Prevention is the best line of defense against invasive pests and diseases. Always be diligent and keep a good eye on your crops so you can spot any problems as soon as they arise.

Take action as quickly as you can to remedy the pest or disease, and only use biopesticides as a last resort and you are at risk of losing your whole crop.

When it is our lucky turn to deal with pests and diseases, I will be documenting which pests and diseases were in our market garden and how we got rid of them.

Keep an eye out for future articles outlining our processes.

How do you handle pests and diseases in your gardens? Let us know in the comments below.

Stay Local,

Kathy & Jon

your friendly neighbourhood growers


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