January 19, 2021

Garden Pests

A Holistic approach to dealing with garden pests and diseases.

Stacks Image 28
Assassin bug (beneficial) on a white fly affected area of a pepper plant.
We can not completely get rid of pests but we can certainly get rid of the frustration, lessen pests and diseases and have a highly productive garden. We often want to quickly get to the point and get quick tips for a garden problem. But for a long term frustration free success in the garden we have to have a different approach. This approach is a holistic one. It creates health in the garden and addresses most of unwanted problems.
The approach begins with a genuine curiosity and in depth learning of the natural processes in the garden. This is the absolute, most essential part when dealing with pest and diseases. When all decisions and actions emerge from this understanding, gardening gets easier and happier.

Plants are complex organisms having variety of defense mechanisms against diseases and pests. Just as we humans need to be in good health to have a good immune system, so do the plants. Their health determines their ability to fight off diseases and pests. Pest problems occur when there is an imbalance between a plant's ability to fight and a pest's ability to attack.

How does this imbalance occur? First we need to understand the complex factors that play a role in health of a garden. Majority of these factors are unknown to us humans at this point in time. To simplify these complex, known and unknown factors, we can divide them into four categories:

  1. Plant factors: few examples are - the variety of plant, the quality of the seed it germinated from and the germination conditions, any genetic mutation that puts the plant at an advantage or disadvantage, any other intrinsic health issues specific to that plant. So many of these factors can not be tested or confirmed. A vast majority others are unknown that have not been discovered yet.
  2. Environmental factors - Larger environmental factors are season, weather, sun, shade, pollution etc. Also very important is the knowledge of environment in the particular garden location and even the immediate vicinity of a plant. Sun, shade, wind, humidity, pollution may vary in locations few feet apart.
  3. Soil and soil life- examples of these factors are - soil nutrients, soil pH, soil pollutants/chemicals, soil life - micro and macro organisms, temperature and moisture of the soil. The nutrients or the organisms we know about are only a fraction of what is actually in the soil. And even more mind boggling is if you imagine the almost unlimited number of ways these factors interact with each other to create different conditions.
  4. Animal life in the garden - animals are all the different insects, lizards, frogs, birds and other small animals. How are the insects (pests and beneficials) and other animals doing in their own worlds at any given time? What larger and smaller environmental factors are affecting the garden animal population that season? We as gardeners do not have answers to most of these questions. Many questions are still being studied and researched by scientists.

So with majority of it being in the unknown realm, should we just let things happen and let nature take its course?
Well, then that wouldn't be gardening if we let nature take its course. When we decided to amend the native soil and grow the plants to our liking, we already started guiding the natural process towards our benefit. To what extent we try to control the natural process, determines the happiness of the gardener and health of the garden.

Here are some things to consider based on the above mentioned four categories of factors:

  • Addressing plant factors
  • 1. A garden journal (text and pictures) to help continue to learn with experience. This way we can remember what variety of plants were in which location and how they performed, if there were any pest or disease issues etc.

  • 2. Try buying from local nurseries which grow plants in their own locations here in El Paso and Las Cruces region (or your local region wherever you are in the US or the world). Even though most nurseries start their plants in greenhouses, the plants that arrived in chain store garden centers may have been started in areas of the US that have very different water and climate than ours.

  • 3. You may find that many of the plants you started at home from seeds are usually tougher than the nursery bought plants of the same variety. The ones started in your home/garden have adapted to your location since germination, and are therefore stronger.

  • 4. Inspect the plants before buying, for any pests or diseases.

  • 5. Avoid buying large plants in tiny containers that are already fruiting. These may often be under stress and root bound.

  • 6. If the sun exposure in the nursery and your garden location is very different, then let the plants adapt to your new location for few days by gradually increasing sun exposure. This avoids sudden stress to the plants.

  • 7. Try transplanting within 2 weeks of purchase to avoid plants getting root bound in their small nursery containers.

Addressing environmental factors

  • 1. Knowing the environment of each and every location of the garden helps tremendously. Know where the sun is at different times of the day and in different seasons. Record in your garden journal about seasonal variations of sun and shade in the garden. Keep in mind the location of trees, large plants, trellises, walls, large planters or any other structures in the yard that affect the sun and shade around it. Bell pepper likes less sun than Okra so planting it on the east side of Okra will give bell pepper some afternoon shade.

  • 2. Planting mixed plant bed with variety of vegetables, flowers, and herbs is very helpful. Diversity protects plants. Pest on a particular plant variety are more likely to cause damage if all plants of same vegetable or same variety are huddled close together in a bed.

  • 3. Watering should be with drip irrigation. In El Paso & Las Cruces region, we have salty water. If plants are watered with large sprinklers or hand watered with hose, salt gets deposited on their leaves which affects the health of the plant. Water on the leaves may also create fungal problems which we fortunately do not deal much with, in our desert climate, compared to other regions with moist climates.

  • 4. Grow plants according to their preferred season. Trying to push a plant through a season it does not prefer, makes it vulnerable to disease and pest attack.

Addressing soil Factors and soil life

  • 1. Alkaline soil in our desert climate makes it difficult to grow veggies. There are soil acidifying agents available in garden centers but the best long lasting solution is to increase the organic matter in the soil by regularly adding compost.

  • 2. Soil texture - whether the soil is rocky, sand or clay, regularly adding organic matter will improve it overtime.

  • 3. Soil nutrition - A variety of organic fertilizers are available in the garden centers and online. It often is confusing what to apply when we don't know exactly what is needed by the plant. Even if you did a soil test for a particular nutrient there is no way to know what other thousands of interactions are occurring among the nutrients and other soil factors/soil life. These interactions affect nutrient absorption. The best method to allow good healthy interactions in the soil is to make the soil rich in organic matter. Compost (plant based or composted manure) is the easiest way to achieve this. If you want to add a fertilizer other than compost then it is better to use the whole product rather than a derivative. For example - use whole bat guano instead of particular nutrients extracted from bat guano and combined with other active plus inactive ingredient to form a fertilizer. Adding a particular nutrient (even if organic), instead of adding the whole product may also cause imbalances we may not be able to judge.

  • 4. Adding chemical fertilizers causes rapid growth of plant which may please us in the short term but the rapid growth weakens a plant's defenses. With the rapid growth, plant has not had time to develop strength and adapt to environment. This makes the plant more susceptible to pests and diseases.

  • 5. Avoid growing same variety of plant in the same location every year.

  • 6. Soil moisture - drip irrigation is a must in our climate.

  • 7. Rainwater is extremely helpful to the health of the soil anywhere in the world. In our desert climate it is even more precious. Rainwater helps to reduce the alkalinity and it also improves the absorption of nutrients from the soil by the plant roots. Collect rainwater in your yard/garden to provide some extra days of rainwater when its not raining from above.

  • 8. Soil cover - Covering the soil with mulch will help minimize the fluctuations in the soil moisture and temperature. Mulch prevents wind erosion of the rich soil you have worked hard to create. It will also help protect the soil organisms from the harsh elements outside. Mulch also provides a slow release of nutrients to the roots and the soil life. Cover crops can be another method to provide soil cover as well as soil nutrition.

  • 9. Avoid stepping or walking in the plant bed which will compact the soil and make it harder for soil life and plant roots.

Addressing animal life in the garden

  • 1. Avoid all chemicals for any purpose, in and around the garden.

  • 2. Avoid all pesticides, even the organic ones. A home made garlic spray or store bought neem oil or any other natural pesticide does not distinguish between insects. Pesticides or seemingly benign sprays will hurt all insects (pests and beneficials) and other garden life.

  • 3. No need to buy beneficial insects. If there are only rare beneficial insects in the garden then the store bought ones are not going to stay in the garden either. They will disappear in a few days. These insects shipped from far away are not native subspecies of our area. The same few species of beneficials are farmed and shipped around the country. In order to encourage diversity it is best to avoid introducing the same species of beneficial insects across all home gardens in the US.

  • 4. Few months after growing a chemical free, diverse garden you will start to see the beneficial insects start to appear. Somehow they discover the garden and show up like magic. These are the ones to stay in your garden. It will be their home. Their population will wax and wane during the year but they will not leave the garden.

  • 5. Observe, look out and read about the insects in your garden. We notice them more when we purposefully look for them and when we know what they are. You may be unnecessarily disappointed thinking there are no beneficial insects when in fact your garden may have multiple species. Some are so tiny that you may never see them. You just see other clues of their presence (parasitic wasp creating aphid mummies is an example).

  • 6. Keep the leaf litter in the plant beds. This helps the insects to hide from predators and protect themselves in harsh weather. If you wonder that leaf litter will be breeding ground for pests, do not worry, insects have their own ecosystem and have their checks and balances. If we keep removing all fallen plant debris from the garden, one thing for sure is that there will be less of the beneficial insects and animals.

  • 7. At the end of season let the leafy greens and herbs go into flowering stage. Let some of these plants stay in the garden bed even as they are drying out (unless you see an aggressive pest on it). These old drying plants often are a favorite breeding destinations for the beneficial insects.

  • 8. When you detect a new insect and have identified it as a pest, do not get alarmed. Just observe and see how nature takes care of it.

  • 9. Observe the pests and plants everyday and learn what changes the pest and plant is going through. Many a times you will be surprised to find how a heavy infestation of aphids, completely covering a branch, slowly starts to turn into a clump of aphid mummies. When the garden has diversity (of plants and animal life) and when we intervene less to change natural processes the beneficial insects in the garden help the plants more than any insecticide ever could.

  • 10. With a heavy infestation removal of a plant or a part of the plant may be required. However it is not necessary in all types heavy infestations. It depends on the type of pest. For most pests you can still continue to observe and majority of the time your will find that after few weeks the plant makes it through the heavy attack. Sometimes a the plant affected may perish but the rest of the garden continues to thrive. The weak plant is what this pest would prefer and they continue to attack that plant leaving others relatively fine. The large population of pests on a plant then also attracts beneficial insects. For example a plant on which you find large number of aphids will often eventually have large number ladybugs and ladybug caterpillars. On a rare occasion there may be a rapidly destructive highly aggressive pest for which you may have to remove the plant.

As we continue to grow our understanding of he natural ecosystem of our garden, we also practice patience. We learn to resist the urge to act on each little change not going according to our liking. Close observation with patience helps us make better decisions when we do need to act. We also have to learn to accept that some plants are going not going to make it no matter how ideal the conditions are in the garden. However, overtime, as the health and diversity of garden grows, the natural processes seem to stabilize. Garden becomes almost on an automatic mode with fewer and fewer issues.