• Marlia Bosques-Martínez

Key practices to manage diseases and pests in your garden: Part 1

By: Marlia Bosques Martinez


There are 3 essential factors that will help you have a healthy farm or garden with minimum diseases and pests. The three factors that we have to focus on are implementing preventative practices, increasing beneficial insects/microbes, and working with the soil. Either you are a gardener or farmer this guide will provide you with simple tactics that are based on agroecological principles and my own experience with gardening and plant pathology research.


Implementing preventative practices

After pests and diseases are established in your growing space it will be much more difficult and cost-effective to manage. For this reason, preventative practices are the most important element all gardeners and farmers should implement in their growing space. Follow these suggestions to have a beautiful bountiful harvest!


  • Create a crop rotation plan for every growing area. Crop rotation is the process of changing which crop you grow in each bed, container, or growing surface. For example, if you decided to grow tomatoes (Solanaceae family) one year, the next year you'd grow in that same area a crop from a totally different family (Brassica family). If you only grow one thing on your farm you can do cover cropping (i.e. legumes or grasses) instead of rotating with another cash crop. This is done to confuse pests (interrupting the pest life cycle) and reduce the risk of soil-borne diseases and at the same time improve diversity and soil health. If interested take a look at this extension fact sheet and SARE’s planning manual.


Crop Rotation. https://www.eagrovision.com/crop-rotation/

  • Decrease possible pest and disease habitats. This includes eliminating most weeds and tall grasses that can harbor many diseases and pests which could be harmful to your crops. Additionally, pests such as cucumber beetles can also overwinter in tall grasses. Make sure you keep the grass mowed around your growing area. Removing plant debris and cleaning all of your tools is also essential to decrease pest and disease populations. All plants that are heavily diseased or covered with pests should be properly removed by chopping, burying, and/or disposing of in a bag. Moreover, cleaning all your tools with a proper disinfectant will prevent from spreading of the disease or pests to another plant. For instance, if you are pruning your cucumbers make sure to disinfect them before using them in another crop.


  • Plant at the correct plant density and prune your plants. Sometimes we want to maximize our space to have more varieties and higher yields. However, planting at close densities makes it easier for pests and diseases to spread more easily and faster. Closely read your seed package plant spacing instructions. Pruning is also highly important for vegetables such as tomatoes and cucumber and for most fruit trees. Pruning improves air circulation through the plant, improves spray coverage, and improves tree or plant vigor. Also, if you have a diseased tree you can also prune the infected part to stop it from spreading. Pruning requirements are different for each plant so when you research, enter the name and cultivar of the plant along the key term “extension” to find free and trustworthy resources. Additionally, consult your local extension literature or agent to make sure you are planting crops at the appropriate time of the year.


  • If needed, plant disease-resistant varieties. Certain areas and seasons may be highly prone to specific diseases such as powdery mildew and bacterial wilt. Additionally, nearby growing areas may spread diseases by wind or water making it even harder to manage. If your growing area is known for a specific disease you can buy or exchange seeds that confer resistance to a specific disease. When a plant already has resistance in its plant immune system this means it will be able to fight off the disease with little or no pesticides. For instance, ‘Verona’ (Organic F1 Tomato Seed) has disease resistance to Fusarium wilt (race 1), Verticillium wilt, and Early blight. In this case, you will have to look out for other tomato diseases such as root-knot nematodes. Check out Disease Resistant Vegetable Varieties for more information.


  • Use row covers to prevent pests. When planting any crops that are susceptible to insects, throw on some row cover (also called insect netting)! Row covers provide a physical barrier to prevent insects from coming in contact with your plant. It can protect against cabbage moths, leaf miners, beetles, cabbage loopers, flea beetles and so much more. There are different types of row covers, so they can also protect against frost, cold, and wind. Put the row cover immediately before plants emerge or right after plants are transplanted. Depending on your growing area you may or may not want to use hoops. For instance in places prone to hail you should use hoops to prevent damage to crops. Remember to support your local agriculture store when buying these materials. Check this extension factsheet for more information about row covers.


Row covers. https://hort.extension.wisc.edu/articles/floating-row-cover/
  • Apply preventive pesticides. Pesticides can be synthetic or organic. Agroecological or organic pesticides usually derive from substances in nature that can be used to control pests. This includes products that come from plants, minerals, and microorganisms. Remember that even though organic pesticides come from a natural source they are in much higher concentrations than they are found in nature. On the other hand, synthetic pesticides are inorganic products that do not contain the element carbon. Both organic and synthetic pesticides are formulated to kill pests products so while organic pesticides are usually less toxic than their synthetic counterparts that doesn’t mean they are safe or won’t cause environmental harm. In some cases, a large amount of organic pesticides is needed to control a pest that may be controlled with a much smaller amount of synthetic pesticides. For these reasons, I would recommend doing the research before making or buying any product to make sure it has been university tested for its efficacy, toxicity, and environmental effects. Check out this resource to understand how to select and use organic pesticides. I also recommend reading this short article to understand the difference between organic, synthetic, natural, and chemical pesticides.


  • Finally, always keeping a watchful eye. This means always monitor your plants for any signs or symptoms of diseases or pests. If you catch the pests or disease early, it will be much easier to manage because you can stop it from spreading to other plants. What I like doing is using sticky yellow traps at the farm. One way to monitor is to put yellow sticky traps around your growing space. You can observe certain pests (i.e. aphids and thrips) and see your sprays or deterrents are working. If you’d like to make your own sticky trap you can use a piece of yellow paper and place tape with the sticky side facing the air. Use this extension fact sheet to diagnose which insect you find in the sticky trap.


Sticky yellow traps for monitoring insect pests. https://www.gardeningknowhow.com/plant-problems/pests/pesticides/sticky-trap-pest-control.htm


Stick around because part 2 will be available in a few days! Part 2 will provide you with great recommendations about increasing beneficial insects/microbes and improving the health of your soil.


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