Vine weevil and Chafer grubs
Exhibitline h is used for the control of Otiorhyncus sulcatus, Black Vine Weevil, larvae feeding on roots in the soil. Adult weevils feed at night producing telltale notches around the edges of leaves and flowers. The root-feeding larvae cause more damage and weaken plants without indication. Slower growing Rhododendrons, Azalias, Camelias and herbaceaous perennials suffer particularly from vine weevil damage.
The best time to use this product is in April/May and in August/September when larvae are active in the soil/compost.
Exhibitline h should be applied when the young grubs can be found in the soil close to the surface. This usually occurs in the months of August and September, it is often dependent on soil conditions. Applications made when the grubs are just below the soil surface are more effective as the grubs will move deeper ito the soil out of the reach of the nematodes after this period.
Soil temperatures must be above 12ºC at the time of application.
Nematodes require soil water to be able to move throughout the soil profile there for it is recommended that the application is made after the soil is already wet through rain or irrigation, it should be kept wet for the following three weeks. Applications made to dry soils in direct sunlight will be much less effective.
Control is achieved by parasitism of the chafer grubs, the effect of this will be seen in the reduction of the grub searching by predators in the spring and direct feeding.
Exibitline h contains 250 million infective juvenile stages of the insect pathogenic (entomopathogenic) nematode Heterorhabditis sp.
The nematodes are supplied as ‘Infective Juveniles’. These seek out suitable hosts by swimming in the thin film of water on soil particles, and they locate hosts by detecting carbon dioxide and other waste products. Once they find a host, they enter the body cavity through the mouth, anus or spiracles, and release bacteria (Xenorhabdus) into the host’s body cavity. These bacteria kill the host within a matter of hours, and the nematodes then grow and reproduce within the ‘broth’ which they produce. The next generation of infective juveniles then leaves the dead host, and moves through the substrate in search of fresh hosts. Infected hosts generally become brown and flaccid as the infection develops, but once dead can be difficult to find in soil. The nematodes are active at temperatures as low as 8°C, but the bacteria which they use to kill their hosts are not: minimum soil/compost temperatures need to be 12°C for the nematodes to work effectively. The bacteria are disabled above 26°C: use in high ambient temperatures can result in failure. The best time to use this product is in April/May and in August/September when larvae are active in the soil/compost.
Exhibitline h contains living organisms that require special handling and application procedure. Follow these instructions carefully to obtain maximum activity. See reverse of this sheet for use instructions.
Drench Application:Preferred method, especially where crop canopy is dense. Make up the Exhibitline h to give a final dilution of 1 pack in 200 litres water. Apply at 4 litres/m². Fig. 1 gives volumes of diluted Exhibitline h required for different pot sizes.
Spray Application:Make up the Exhibitline h to give a final dilution of 1 pack in 50 litres water if treating open soil, or 1 pack in 100 litres water if treating pots/containers. Apply at 1 litre/m².
Knapsack sprayer:Make up Exhibitline h to give one pack in 10 litres water, then dilute this stock solution as Fig. 2.
Pot diameter (cm)
Exhibitline h drench per pot (mls)
No. pots treated per pack
1 part Exhibitline hm solution + 19 parts water
1 part Exhibitline hm solution + 39 parts water
Apply at 4 litres per sq.m.
1 part Exhibitline hm solution + 4 parts water
1 part Exhibitline hm solution + 9 parts water
Apply at 1 litre per sq.m.