BASF launches biological control of vine weevil in strawberries

Developing Integrated Pest Management solutions as well as alternative approaches and techniques are central principles of the recently introduced Sustainable Use of Pesticides Directive (SUD). Growers of strawberries and raspberries have an amazing tool to control vine weevil that will not only do the job well, but will also comply with this important piece of legislation.

“Nemasys L (Steinermema kraussei) is an insect-parasitic nematode that controls immature stages of the Black Vine Weevil in strawberries and other crops under a wide range of temperatures. It is preferable to use biological control for vine weevil and recent independent studies have reiterated that Nemasys L is the best weevil product on the market,” says Dr Aoife Dillon of BASF Agricultural Specialities.

Black Vine Weevil (Otiorhynchus sulcatus) is a devastating pest of many plants, particularly soft fruits and nursery stock. In strawberries alone they are said to be responsible for losses of over £10 million p.a. The adult feeds on the foliage producing characteristic notches, which is more of a problem in nursery stock where cosmetic damage can make the plants unmarketable. “It is the larvae in the soil or growing medium that cause the most economic damage, feeding on roots, leading to wilting or even death of the plant. When applied as a drench or through irrigation systems, Nemasys L controls the damaging larvae rapidly and safely across a soil temperature range of 5 to 30ºC.This assured activity across a wide temperature range is what differentiates Nemasys L from other biological competitors such as other nematode products and Metarhizium anisopliae, which are not effective at lower temperatures,” comments Aoife.

In ADAS/HDC trials strawberry plants in coir substrate, the Nemasys L treatment, applied in September, reduced the weevil population by 96-97%. The number of weevil larvae in grow bags treated with Nemasys L was reduced to less than 2 larvae per grow-bag, compared to up to 44 larvae per bag where nematodes were not used.

Aoife Dillon explains that the adult vine weevil is active from the end of June through to October. The adult female lays 1000 eggs in the soil or compost from July through to September. The eggs are 1mm across, white turning brown and are difficult to see. Larvae hatch after 2 weeks and start feeding on plant roots. The larvae pupate in late spring and emerge from June onwards. The beneficial nematodes seek out the vine weevil larvae and once inside release symbiotic bacteria, quickly killing the insect pest. The microscopic nematodes reproduce inside the insect and release a new generation of infective juveniles that seek further larvae, providing long lasting effects.

Nemasys L is applied with standard spray applicators from February to November when the vine weevil larvae are present and soil temperatures are above 5ºC. In addition to being effective at warm and low temperatures, Nemasys L has no resistance problems, no residue concerns, no non re-entry interval, no requirement for protective clothing and no disposal restrictions.

Rob Storer, Speciality Crop Manager for BASF, notes that “undoubtedly there is increasing pressure for effective pest and disease control in specialist crops, particularly fruit crops, but there are more legislative and practical challenges for growers. We need effective alternative options to boost yield and protect quality in these speciality crops and Nemasys L does just this. BASF are developing market-leading science in both conventional and biological approaches, along with a combined approach to plant treatment.”

He says that BASF are fully committed to both horticulture and agriculture and that the integration of world-leading biopesticide technology fits well into the company’s quest for “Innovation beyond Crop Protection.”