November is the first time we see a significant change in the weather in South Florida. This wonderful month usually brings in the very first cold front and consistently lower night time temperatures. Even though the changes in degrees are slight, they can make a world of difference in a garden. Just 5 degrees cooler throughout the night can help to slow down pest life cycles enough to take some of the pressure off of the gardener to keep a vigilant eye on pest issues.
That said, pest issues are always going to be a problem, whether your garden is organic or not. People often ask us what they could do to prevent pests. If only it was simple enough to be able to answer that question. The truth is that pest management is a science and way more complicated than anyone ever wants to believe. There is no one ticket to success, in fact the professional term used in organic gardening and farming for pest management is IPM, integrated pest management. IPM is about the idea that when battling a pest issue one should think of the big picture and look at all of the natural factors at play creating that pest issue, integrating multiple actions to remedy the issue. For example, instead of shopping for a quick fix spray to kill off a bug, think things through, observe and take multiple actions to try to balance the natural relationships occurring in your garden.
Start by zooming way out and considering the most basic needs of your plants. Sun, oxygen, water, nutrients and whether or not a particular plant variety is in season or not. When a plant is experiencing stress from lack of a basic need it becomes exponentially more susceptible to pests. Do you need to consider moving your garden to a sunnier location? Or can you prune a large tree on your property to allow more winter sunlight through? Do you need to re-pot your plants in better draining soil so that the plant roots are getting enough oxygen? Did you know that plants need oxygen just as much as they need water? The microbial life in your soil also needs a balance between oxygen and water. The way to achieve that is by using a soil mix that absorbs water like a sponge, but also drains excess water quickly where air pockets can form around plant roots. Soil is all about texture! If you are a beginner you may need to be patient and keep experimenting until you get a feel for the right texture. The soil mix we use for plants at our nursery is different than the soil we use for garden installations, but they both have a lot of peat for that sponge water holding quality and they have different particles for creating drainage. Healthy roots should look really white and thin. Yellow roots are a sign that your soil may not be draining well and your plant roots could be rotting.
Now lets remember that IPM (integrated pest management) looks at several factors that are causing a problem and you should be ready to take multiple actions. Sometimes a good way to get more light and air flow in and around your plants is to prune away some foliage. This might kill two birds with one stone. Pruning away infested leaves is actually the first line of defense against most pest issues, especially insect infestations such as aphids, white fly, mealy bugs and spider mites. All of these insects fall under the "piercing and sucking" category and they tend to cling to the leaves of plants, particularly on tender growing tips as well as undersides of largest oldest leaves. Check those areas first and prune away any plant parts that are visibly covered in bugs. By doing this you've already reduced the pest population by a huge percentage.
One of the most important exceptions to this rule is when you have a plant infected with a virus! Viral infections are typically not curable and plants showing signs of a virus should be entirely removed from your garden and thrown away. Clean your hands and tools with a disinfectant soap before working on healthy plants to prevent the spread of the virus. Leaving a virus infected plant in your garden causes other plants to become infected through your touch or by insects that visit an infected plants and then visit a healthy plant.
Even in IPM there is room for spraying. We spray with organic products when it makes sense to do so. The key is to use these products wisely and in combination with other actions to remediate the problem in a wholistic way. What happens when someone simply sprays for a pest issue is that the pest problem inevitably comes back again and again, if it is ever solved at all.
Here's our guide to common garden pests and how to treat them:
Very common. soft bodied insect, can be light green, yellow, black, grey. feed on a variety of plants, commonly found on leafy greens. cluster mostly on new growth, secret a sugary fluid called “honeydew” that makes food crops less appetizing and is also eaten by ants. Ants will occasionally farm aphids on your garden plants, they will pick them up and place them on your plant and then tend to them and harvest their honeydew for food.
Treatment: there are a ton of home remedies online however we rely on spraying Neem Oil mixed with water and a bit of organic soap. the soap is important to help mix the oil with the water. spray plant heavily, target the bugs you want the neem to hit them not just the leaves. Keep your plant cleanly trimmed, remove dead or old leaves where the bugs will hang out, and spray often, not just once. A key to most pest management strategies is doing them more than once! Ladybugs are predatory insects that feed on aphids. If you want to increase your ladybug population they can be bought online and released in the garden.
If you’ve ever grown tomatoes then you’ve seen a hornworm! no matter where you are growing your tomatoes hornworms are sure to find your plants. large juicy bright green worms with a horn on their butt feast on young and tender growth, so when you see new shoots and tips being stripped of their foliage then examine your plant for hornworms. Tomato hornworms affect all plants in the solanaceae family: tomatoes, peppers, eggplants, potatoes
Treatment: BT aka thuricide is the best way to treat hornworms, and any other worms that may be eating your plants. BT works when sprayed directly on the worm by disrupting its digestive cycle and causing starvation. You know your BT has killed your worm infestation when you see them hanging from your plants, shriveled and brown. Your other main option is going through and picking them all off the plant, however they can be VERY EASY to miss, since they are so well camouflaged. Note: a hornworm with small white objects that look like grains of rice stuck to their back has been “parasitized” by a beneficial wasp. Leave parasitized hornworms, the wasp babies will kill them when born.
Scale are small hard bodied bugs that don’t even really look like living organisms. They appear as small green or brown bumps on the stems and branches of plants like eggplants, peppers, and some fruit trees like mulberry and loquat. Scale slowly reduces the overall vigor and healthiness of a plant.
Treatment: Neem Oil can be sprayed on them, when we see them we run our (gloved) hand down the stem of the plant to kill them manually.
Mites can be quite a hidden terror in south florida. They are so small they can’t be seen by the naked eye, and they negatively affect the growth of a slew of crops, including: tomatoes, peppers, eggplants, arugula, papaya, roselle, okra, sage, mint... the list goes on. We have a major “two spotted spider mite” problem at the farm that prevents us from growing many summer crops, since their populations balloon during the hot and wet months. Unfortunately symptoms vary based on plant, however there are two common ones: a rippling or shriveling distortion of new growth tips, and a peppering of white or yellow dots on the leaves of the plant. Mites suck the moisture out of individual plant cells, killing that cell, which is what causes the tiny dots of discoloration. If you have a pest issue and you dont see any pests, think mites... we see signs of them at almost every home garden we visit. Mites can also ruin the fruit of tomatoes, eggplants and peppers by causing parts of them to be coated with a brown suede-like growth.
Treatment: We treat our mite issue with regular spraying of the following miticides:
Bonide Captain Jacks Dead Bug Brew- the active ingredient is Spinosad, originally derived from a soil born bacteria. This is a great broad spectrum spray to have for your garden as it also kills beetles, caterpillars, thrips and more.
M-PEDE insecticidal soap- this is another broad spectrum staple in organic farming, as its a miticide, insecticide and fungicide. it works as a smothering agent, so it must contact the bug in order to kill it. when spraying on your plant make sure to coat thoroughly including the underside of the leaves. Organic and Biodegradable, make sure to spray in the morning or evening, and if it rains afterwards you need to spray again. When managing an outbreak plants need to be sprayed at least once a week until bug population is decreased.
Stink bugs come in a variety of shapes, colors and sizes but the most common ones we have at the farm are either small shield shaped bright green hard bodied bugs, or larger black ones with long legs and large black bodies. You can tell if its a STINK bug if it smells very bad when you squish it. Stinkbugs are most commonly found on tomato and eggplants, where they like to suck the juice out of the fruit making it ripen improperly. Stink bug young, aka “nymphs” are tiny red ant-like bugs that hang out in clusters.
Treatment: Stink bugs are very aware of their surroundings, once they see you they will run from you, hide on the underside of leaves, corral their young into safer areas of the plant, and they will “play dead” when you hit them by dropping off the plant onto the ground to make you think that you got them. Squishing them (with a glove on) is a good solution for smaller outbreaks. Plants can be dusted with Diatemaceous Earth, which cuts up their bodies when they land on the plant, although if the DE gets wet it won’t work and will need to be reapplied. A creative solution we have tried: using a dust buster to vacuum them off the plant... it really works but can be tedious
Leaf miners are the larvae of common black flies, and are very commonly found on tomatoes, nasturtiums, many leafy greens, basil and lemon balm. They create tunnels through the leaf of the plant that turns dark or light as the plant dies where the tunnel was. Once the larvae has matured in its tunnel it will burst out of the plant and fly away, although sometimes when you open the tunnel you can see the larvae.
Treatment: leaf miners are not a big deal and many plants can out grow them. When a plant is healthy and vigorous it can support some leaf miners and not suffer. We rarely treat for leaf miners, and we have amended our crop list to not include basil or lemon balm because they love those plants so much, instead of spraying insecticidal soap.
Nematodes are the scourge of south florida gardening. they are present in all types of soil, and thrive here because they like sandy low-organic matter soil. They are an invisible ringworm that feeds on the roots of plants causing a general weakening of the plant and sometimes death, depending on the density of nematode population. Its hard to tell if you have nematodes or not until you pull the plant out of the ground: nematode affected roots are brittle and thick, covered with many small nodules and bumps.
Treatment: there isn’t an easy solution for nematodes which is one reason why they are such a problem. If you know you have nematodes, try planting resistant plant species. Areas of your garden can be Solarized to help reduce their population. The most common and affective way to reduce nematode population is to increase the soils organic matter content, so if you’re battling nematodes we would recommend solarizing your soil for about 6-8 weeks of summer and then tilling in/ incorporating broken down mulch or compost before planting season. Beneficial nematodes are another option that some websites recommend however we have been told that the beneficial nematodes dont thrive in our climate so they will be unlikely to out compete your bad nematodes. There is a cover crops that is “nematocidal”, meaning they reduce nematode populations, called Nematocidal marigolds (more information here: http://www.ctahr.hawaii.edu/ oc/freepubs/pdf/PD-35.pdf)
Slugs and snails are luckily not a big issue here during the winter season but they do exist. Typical behavior includes hiding in dark moist areas like under rocks and borders and then coming out at night to feed on your plants while you sleep. Damage to plants will be small holes or chunks of leaves missing, or whole seedlings mowed down just as they appear popping out of the soil. Snails often leave trails of mucous that can also be used to diagnose whats eating your plant.
Treatment: a good way to reduce their population is to go out at night with a flashlight and either pick them off your plants, or sprinkle them with salt. Traps can be set in your garden, there are a few different traditional techniques. One we have had success with is filling a shallow dish with beer and burying it in your garden just until the lip of the dish is at the same level as the soil. The snails will climb into the dish to feast on the sugars in the beer and they will drown. There are a number of organic slug baits on the market that can be spread throughout the garden.
Whitefly is a very common small white winged bug found throughout Miami on many ornamentals, fruit trees, and vegetable plants. They are very common in home gardens because of the popularity of ficus trees in ornamental landscaping, and can be found on the underside of tomato, pepper, and sweet potato plants. Whitefly also produces honeydew, which can cause black sooty mold, another pesky garden foe.
Treatment: remove infested leaves and then spray with an insecticidal soap, like M-PEDE. you will need to spray regularly to combat their populations as new groups of them will drift into your garden throughout the season
Mealybugs are small bugs that appear in clusters on the underside of leaves and on the stems of plants clumped in the forks of twigs and branches where they suck plant juices as food. Mealy bugs are white ovals that cover themselves in white webbing/dust. Large clumps of mealybugs can resemble lint or cotton stuck to your plant. They are most commonly found in Miami on plants in the hibiscus family: roselle, okra, ornamental hibiscus, and cranberry hibiscus, but they also like tomatoes, peppers, and fruit trees. Another symptom of a mealy bug problem is very distorted new growth on the plants tips. A plant will continue to grow however the leaves and stems won’t move, so a knot of plant material will form looking all crumpled and twisted.
Treatment: remove the affected plant matter by cutting and trimming (dont forget to discard the cuttings properly, dont just throw them on the ground or in your compost pile) and then spray with Neem Oil.