First thing in the morning, we headed towards the interior of Guyana, where we visited a coconut, pineapple, and other smaller ‘cash crop’ farms. The most important pest brought to our attention was the devastation being caused by a rhinoceros beetle; a beetle that bores at the base of the coconut trees and into the main stem, resulting in total tree mortality. The growers said they have lost about 50% of their coconut trees to the rhinoceros beetle! The bore holes always appear to be right at the stem of the coconut tree. This problem made me think of the Diaprepes root weevil problem in Texas; a beetle that kills citrus plants by laying eggs on the leaves, and the larvae fall onto the soil below, burrow into the ground, and feed on the roots. Research at Texas A&M demonstrated that the weevil could be stopped by using a plastic mesh over the soil, which prevents the larvae from being able to burrow down below and the larvae subsequently die. In theory, this same solution should work to prevent the rhinoceros beetle from getting into the trees – I proposed this as a solution to the coconut growers and hopefully provides some promising results.
Next, we visited a region of Guyana that is known for producing chives and lettuce – most of the growers in that small area specialize on those two crops. Many of these growers are small acreage, growing mainly in their backyards in beds or shade-houses. We identified many different crop challenges, including leaf-miners, root-knot nematodes, and mealybugs. The leaf-miner appears to be a species within the genus Liriomyza– a fly that spends its larval stage between the upper and lower leaf tissue, making it really challenging to control with insecticides and tend to produce scars on leaves even if you do manage them. The mealybugs are difficult to notice until too late, as this particular group appears to feed on the roots. Root-feeding mealybugs will reduce the growth and uptake efficiency of the roots, resulting in above-ground effects but with no obvious culprits (until you take the plant out of the ground!).
We saw the root-knot nematodes at some farms the day before too – so this problem is relatively widespread, it seems. One method of killing nematodes within a bed is to use the soil solarization technique – a method that involves using clear plastic to cover a bed and allow the sun to essentially ‘cook’ the bed completely of weed seeds, nematodes, insect eggs, and bacteria. They have access to clear plastic here at the local agricultural supply stores, making this a possible option for future nematode control.
Although I provide the growers with some solutions as we are making observations on their farm, the purpose of this week is really to make observations in order to develop the training programs for next week. I will be developing more specific diagnoses and multiple solutions to each challenge they are facing, with the hopes that they find at least one that is suitable and works reliably to reduce crop yield loss.