In advance of our class this Saturday (March 19 from 2-4pm) on defending your garden from snails, slugs, and plant-suckers, we have a guest post from the teacher, Teresa Lavell, a certified IPM Advocate who works with water agencies in the Bay Area to promote cleaner waterways by educating home gardeners on less-toxic solutions for their gardening problems.
Have you heard the term IPM or Integrated Pest Management? Too often people think it is simply a matter of not spraying or using less-toxic pesticides to control problems in the garden. It is a much bigger picture than that. IPM is an approach to gardening that takes a wider look at what might be happening in the garden and based on some simple questions determines a path from there.
First and foremost, IPM is about properly identifying a situation. We are often inclined to associate damage with whatever insect might be present when we see the damage. What if, for instance, you find holes in a leaf? Could the culprit be the beetle flying near the plant? Or maybe it is a fungus that caused the damage? Or maybe even a fluke hail storm! Applying a pesticide without diagnosing what actually happened might not be just ineffective but it may even be counterproductive by killing off beneficial insects in the area without addressing the real problem. Yellowing leaves on a plant could be anything from too much water, not enough water, fungal infection, sunburn or nutritional deficiencies. Taking the time to properly diagnose the situation will not only save time but money as well.
Once you have figured out what the actual issue might be in your yard, the next step is determining a tolerance level. When dealing with aphids on roses for instance, instead of having a zero tolerance policy, perhaps you can wash them off with a full stream of water until the beneficial insect population blooms to take care of them. There is always a lag time between the appearance of pests and the predators that will eat them. A bit of tolerance on the part of the gardener will allow nature to take its course.
Citrus leaf miner – yet another invasive species in our area- is becoming a bigger issue for home gardeners. The mature insect is a small, light-colored moth that lays its singular egg on the underside of new, tender citrus foliage. Once the egg hatches the larva starts feasting on tissue inside the leaf. The tunnels that are created are easy to follow as the larva grows. People see these marks and want to kill the culprit. But, for the home gardener, this is mostly an aesthetic problem. Unless the plant is very young with a major infestation, no treatment is necessary. Simply pinching the leaf where the larva is eating will kill it before it pupates. Tolerating some damage to the leaves of the plant doesn’t affect the outcome that we want – a lovely citrus crop.
But what if the pest is identified as something that will affect a desired outcome? What if you have an apple tree that had an infestation of codling moth last year and you lost most your harvest to worms? The IPM approach is to start with good sanitation and monitoring. Make sure all dropped fruit is disposed of properly. In addition, if you see fruit with signs of infestation (excrement filled holes) remove them before the larva has time to exit and reproduce. One of the reasons some pesticides are considered less toxic is that they are less persistent in the environment. This means they have a shorter window of toxicity so monitoring for timing is critical. There are pheromone traps available that you can set out to help determine when the adult moths are active. Once you determine if and when there is a threat, you can spray with a product containing Spinosad – a less-toxic ingredient that is safer for beneficials, pets, people and the environment (visit the UC IPM pest note on codling moth for further details on spraying).
Of course there are more questions that can be asked about the above scenarios. How could you avoid the problems in the first place? Was there an application of a broad-spectrum pesticide that killed off beneficials that allowed the aphids to prosper? Did improper pruning or over fertilizing cause the flush of new growth that attracted the aphids and citrus leaf miner? Could a different variety decrease the probability of attracting the codling moth? IPM takes a multi-directional approach to challenges in the garden and attempts to find a healthy, sustainable solution.
Come to the class this Saturday (March 19 from 2-4pm) to ask Teresa all of your burning plant pest questions, for only $5!
Register online here.