Exacerbating the effects of a poor growing season, horticultural producers reported an explosion of aphid numbers earlier this summer. This is attributed to the exceptionally cold spell last winter followed by the warm spell in April.
Natural predators of aphids such as ladybirds and hoverflies may have been killed off by the exceptionally cold winter temperatures, allowing the pests to breed, uncontrolled. Aphids can breed at under a week and can live for up to two months, producing several broods of up to fifty young. As well as sucking sap from plants and depositing sticky honeydew, aphids can spread viruses and other diseases between plants. It appears, however, that ladybirds are benefiting from the extra food supply and larger than usual numbers have appeared during the summer, albeit too late to control the first big flush of greenfly.
Similar reports have come from the UK where higher temperatures have intensified the problem and large numbers of greenfly and blackfly have been reported in urban areas.
It’s “the single largest threat to production agriculture that we have ever seen,” says Andrew Wargo III, president of the Arkansas Association of Conservation Districts, speaking about the proliferation of superweeds throughout the US. The weeds have mutated to develop resistance to herbicides such as Roundup and a range of other commonly used herbicides and are spreading resistant traits to other plants through pollination. A series of studies published in the journal Weed Science report that there are currently twenty-one different weed species known to be resistant to Roundup and the acreage of farmland known to be infested is eleven million acres. There are reports that some weeds are growing up to three inches a day and ruining farm machinery.
Farmers have resorted to hand weeding and the use of different herbicides in an effort to control the weeds, costing more in time and money than if they had never planted GM crops in the first place.