Have you ever been bitten by a mosquito? The bite can be annoying, and in some cases, it can cause an allergic reaction, welts. While feeding, mosquitos also transmit harmful diseases. Did you know that our garden plants have their own mosquito-type vampires? These pest insects attack plants in a similar fashion by draining the sugar-rich “blood” of our beloved green friends. During their sweet feeding frenzy, some of these insects can also transmit diseases. Through the spread of disease, these plant vampires cause significant problems in gardens and landscapes throughout Manatee County. To mount a successful defense, one must first identify the “vampire” insects, which diseases they can spread, and be ready to prevent or manage the disease if it shows up.
Introducing the plant vampires
To begin with, one must first understand what these plant “vampires” are. One thing these insects have in common is piercing/sucking mouthparts. These are similar in structure to a mosquito’s mouthpart. They are designed to pierce the plant’s tissue, then suck out the sugary, nutritious fluid from within. This feeding is usually done with such vigor that excess fluid is released from the attacker’s abdomen (as excrement) and falls upon the lower leaves and stems. The excess droplets are sticky (from the sugary sap) and attract a fungal organism. Where the droplets and fungi meld on the leaves, a black film-like mold forms; we refer to it as sooty mold. There are several insects that release the sticky excrement causing sooty mold. Let us talk about the three insects which are very good at transmitting diseases. Aphids, whiteflies, and psyllids are all documented to spread plant disease through feeding activities.
Correspondingly, each disease the insects transmit have some tell-tale signs. For example, aphids are one of the most efficient, and common, vectors of plant diseases. They have been documented to transmit well over 100 plant viruses. Cucumber mosaic virus, which is transmitted by aphid feeding activity, causes a distinct leaf pattern on cucumbers. Psyllids, specifically the Asian citrus psyllid, transmit a bacterium that causes citrus greening. This plant disease shows up in citrus trees as an uneven mottling of yellow and green on the leaves and poor-quality fruit, among other signs. Finally, whiteflies are common pests of tomatoes. While feeding, they may transmit Tomato Yellow Leaf Curl Virus which can severely impact tomato harvest. Fruit size reduction or elimination, yellow, crinkled new growth, and reduced plant vigor are signs and symptoms of the whitefly transmitted virus.
A little IPM goes a long way
Despite insect’s tendency to transmit diseases, most of the plant vampires can be managed with some effort. Utilizing integrated pest management strategies, often called IPM, you can begin to fight back against these troublesome pests. IPM consists of four steps of management. First, we look at the cultural management strategies. Cultural management include plant selection, watering frequency, and fertilization. Second in the plan are the biological management strategies. We use predatory or beneficial insects, mites, or fungi to manage pest insects. Third are the mechanical management strategies. Mechanical controls are simply squishing, pruning, or removing pests by hand. Fourth in the IPM steps is chemical management. Remember the “I” in IPM refers to the integration of several methods to manage pest insects. Chemical control has a role in IPM and if you are using steps one through three, chemical control can be used as a preventive measure starting with the least toxic options first. Neem oil, insecticidal soaps, and horticultural oils are examples of the least toxic options.
Scout your landscape
In conclusion, plant vampires are common pests on vegetables, fruits, and landscape plants. They come in many shapes, sizes, and colors, but in common, they all have piercing/sucking mouthparts. With their needle-like mouthparts, they can feed on many plant species and, in some cases, transmit plant diseases. Fortunately, using the IPM steps, most of these pests can be effectively managed. So, the next time you see aphids attacking your plants, remember that they are sucking them dry…just like a vampire.
Looking for more…
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Of course, if this topic intrigues you, watch for our upcoming workshop on Plant Vampires. Contact Mack to be put on the waiting list for attendance. 941-722-4524, extension 1821. Are you interested in other workshops? Check out our county calendar of events: Manatee’s Calendar of Events.
Article contents written by Mack Lessig, UF/IFAS Manatee County, editing by Lisa Hickey, Sustainable Ag and Food Systems Extension Agent. Contact us if you need additional information firstname.lastname@example.org (941-722-4524 extension 1821) or Lisa.Hickey@ufl.edu (same number with extension 1817.)