Managing Pest in Your Garden: Part II
/Welcome back! Last week we talked about all the steps you take before actually taking any action against your pests. If you haven’t read that post yet, click here, then come back!
This week, we’ll talk about the 4 ways that you can safely manage pests in your garden. An important part of learning about the pests you are dealing with, are learning more about their life cycle and how to interrupt it. This is as simple as removing a seeding weed before the seed heads develop. With a flying insect, like a white cabbage moth, this means protecting your plant from the month so it cannot land on your crop and lay eggs. By not allowing the pest to reproduce, you are very effectively removing it.
Once you have completed the first 4 steps outlined last week, and have decided that you really can’t live with your current pest problem, it’s time to think about taking more serious action. In the world of IPM (Integrated Pest Management - the methodology we use at GFE), there are four ways to combat pests. These are called controls: Cultural, Biological, Mechanical and Chemical.
Cultural Controls
The first thing I would suggest trying is a cultural control. This is changing the “culture” of where and how your plant is growing. I mentioned last week the GFE motto - Right Plant Right Place. Thoughtfully choosing the right plant for each location is the best pest prevention strategy you can have. Plants that are naturally adapted to thrive in their location will need less interventions and have less problems. If you are practicing this principle - congrats! You are successfully using a cultural control in your garden.
Baby lettuces grow along drip irrigation under floating row cover in at gfe
Another great cultural control is water. Look at your plant! Is it getting too much water, or maybe too little? If it is on drip irrigation line, is your line clogged? We often seen vegetables at the end of our beds looking sad and not thriving. When water moves through a drip irrigation line, things like dirt and small rocks can often get in the line and because of pressure, this dirt and rocks are pushed to the end of the irrigation line.
Some plants that fail to thrive are getting too much water. Many plants we grow here in the Bay Area are adapted to thrive without much water and too much water can cause root rot and attract things like fungus. This overwatering is hurting the plants ability to thrive, and a plant that is not thriving is susceptible to pests.
Also, consider when you are planting your plants. If you plant a perennial in the heart of our dry season (summer) the warm soil and lack of moisture may never allow it to thrive. Consider planting perennials in Nov - Feb to ensure the best success.
With vegetables this is also vital. Pests tend to be specific to particular plant families, and pests can be very seasonal. Our planting calendar recommendations, that we get from Pam Peirce’s amazing book Golden Gate Gardening, take this into consideration. Warmer weather makes some pests come out of hiding, and for others it diminishes its populations. One year, I planted our green beans starts in late April, only to have a very cold May in San Francisco. They never took off, needing warmer weather to grow. Be thoughtful about when you plant your plants and you can change the outcome!
Biological Controls
The second recommended “control” for your garden is biological. This is using the natural biology of an ecological system to help control pests. One example of a biological control? Planting a thriving perennial border or flowering plants that will attract a diversity of ecological life. The key here, as organic gardeners, is biodiversity.
Sweet alyssum, photo from Johnny’s Select Seeds
Another way to use a biological control in your garden is to use plants to attract beneficial insects that will help manage any pest outbreaks you might have. For example, a common small flowering plant called Sweet alyssum attracts hover flies who in turn eat aphids. This is a wonderful plant to have in your garden. California black sage, Salvia mellifera, is a host plant for ladybug larvae, another great insect to have in your garden. By using plants to attract more biodiversity we can add beauty and health to our garden.
An important population of our biological controls for city living, are sadly in short supply. Larger predatory birds such as hawks, falcons and owls have sadly faced diminishing populations over the years. Rat poisons, purchased by gardeners and homeowners to control rodent populations, have had devastating secondary effects. Large birds that eat the rodents infected with these toxic chemicals are killed. By trying to control a population with dangerous chemicals, we have actually worsened the problem by killing the predators of those same pests. This is a big part of why we practice gardening the way we do at GFE. We know that every decision we make can have downstream effects. How can we practice gardening in a way that provides as little harmful disruption as possible?
The good news is we are seeing more and more hawks at GFE in recent years. Glen Canyon has owl fledglings each spring and more and more people are building owl boxes. As we change our use of toxic chemicals, we can bring back the healthy biodiversity that support a thriving garden and urban ecosystem.
One last note on biological controls. Purchasing some of these are in our experience, ineffective. Coyote pee doesn’t have a strong track record and if you purchase ladybugs, well they have wings and can fly off. We have found it better to build a thriving garden that will naturally attract and support this diversity of creatures.
Mechanical Controls
Mechanical controls are an incredibly effective tool for controlling pests and we have lots of examples of them in the garden. Mechanical controls are essentially some sort of barrier between your pest and your plant. The most basic example of this? A greenhouse! The structure of a greenhouse protects fragile, baby plants from anything that may want to harm them.
Floating row cover at GFE helps to keep out flying insects like aphids and white cabbage moths.
We have a lot of effective mechanical controls at the garden and they have few downstream effects. We build raised beds for our vegetables and line them with 1/4” galvanized gopher wire to keep the gophers out. A simple and effective mechanical control. While brassicas (kale, cabbage, broccoli) are developing we cover them in floating row cover, a thin white cloth that keeps flying insects out, but lets light and air in. White cabbage months are common and can be particularly devastating for brassica crops; We cover tender lettuces and ripening fruit trees with netting to keep the birds out. And, while we don’t always feel great about it, we do trap and kill particularly tenacious rodents that can wreck havoc on our garden. These are all examples of mechanical controls.
Chemical Controls + “Shovel Pruning”
The final step in a traditional IPM approach is a chemical control. The idea is, you have tried everything possible, every one of the 7 steps listed on these two posts, but your plant just is not thriving. This is when some gardeners may turn to a chemical solution to remove the pest problem.
We here at GFE, have another approach. If we have tried everything - evaluated the plant location, adjusted irrigation, protected the plant and supported it and it simply won’t thrive? We remove it - or shovel prune :) We are not a large farm working on slim margins trying to feed our families and keep our business afloat. We are small urban gardeners and if a plant is not thriving despite all our attempts, we determine it is not the right plant for that location, and we find something that is. Removing a plant can be a liberating choice - we do not need to keep everything, just because it is in the ground. Often, removing sick or pest plagued plant keeps our garden healthier and looking more beautiful.
There are just a couple chemical controls we will use at GFE and they all have one thing in common - we would put them all down our kitchen sink. A small amount of dish soap in a spray bottle is an effective tool against aphids. And baking soda solutions can be helpful to combat some fungal diseases. But that is it.
Pests will always be part of gardeners experience, and a reminder that we garden in the natural world. GFE is an example that we can have a thriving, healthy garden that follows the principle of right plant right place, and still produce food for us, and all our critters big and small to eat. Let’s create more - more habitat, more biodiversity, more living things in our City.
