A Day in the Life of a Qualitree Pest Scout

Fungus Gnats
My work day at Qualitree as a pest scout begins by checking the sticky cards in each greenhouse. Sticky cards (see below) are a great way of monitoring pest population levels as well as getting an idea of all winged insects that are in the area, pests as well as beneficials. The first sticky card I look at may have several adult fungus gnats stuck to it. Although the adults don’t do any damage this is a problem because the larvae feed on the roots and vector root diseases such as Pythium and Phytophthera. These larvae are predated on by the natural occurring rove beetle which is considered a beneficial. After checking several plugs, if I find fungus gnat larvae I will decide to apply a predatory mite, Stratiolaelaps scimitus, to the affected greenhouses as it will help the rove beetle keep the larvae in check.

Walking into a greenhouse filled with Lavandula, I am looking for any signs of potential threats or pests. If I notice a few plants with crinkled leaves I immediately suspect aphids because I know that aphids inject a toxin into the plants while feeding that causes this distortion of the leaves.  Upon further inspection of my initial thought It is likely that I’ll find brightly coloured green peach aphids hidden among the new growth of the plants. A golden aphid mummy attached to one of the leaves alerts me to the presence of a parasitic wasp, most likely Aphidius colemanii. This wasp is a beneficial as it helps us keep the aphid population at bay. The female wasp lays an egg inside a live aphid which will eventually hatch and the larvae feeds on the aphid’s insides, leaving the vital organs for last in order to keep the food source as long as possible. After about two weeks the pupae hatch and the adult wasp cuts her way out of the leftover skeleton. This parasitoid is an effective natural way to keep the aphid population under control. If I notice that the population of aphids is low, I would not suggest any treatments but will continue to monitor the population levels.

Soldier Beetles
Heading outside now that the dew has lifted off the plants, I begin by inspecting our Picea crop. Near the tip of one of the plants I find a red and black beetle. After doing a little research I find out that it is not a pest but actually a beneficial generalist predator that feeds on aphids, among other things. The soldier beetle will help me keep the aphid population outside in check.

Record Keeping
After spending the rest of the day scouting outdoors, my work is not finished. Filling in a detailed scouting report and discussing my findings with the section growers is an important part of a complete IPM program. I will discuss a treatment plan with them if necessary and document the results of the treatment. Researching insects unknown to me and familiarizing myself with them allows me to make informed pest management decisions.

What are Sticky Cards?
Sticky cards often have a wide array of insects on them. These cards are used in conjunction with other scouting techniques to inform us of pest populations as well as environmental factors. For example, the presence of fungus gnats and drain flies indicates high moisture levels. Using cultural controls such as reducing the amount of irrigation water and eliminating any puddles or other wet spots is a very important part of the IPM program that doesn’t include using chemical treatment.

Noticing winged aphids on the cards suggests a large population of aphids in the crop; when these insects are overcrowded wing development is triggered on the adults.

A good IPM program promotes biodiversity. A good pest scout acknowledges that a balance between pest and beneficial species is necessary to maintain the beneficial population levels. When intervention is necessary we choose the safest and most targeted chemistry available to protect the environment we live and work in each day.

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