The Canadian company Van Geest Bros. Limited was confronted with a very serious outbreak of mealy bug. However, Koppert Biological Systems's Cryptobug provided the solution, with a severely stunted crop saved and recovering well.
Van Geest Bros. Limited is a family company specialized in the production of the highest-quality cut flowers. It is managed by the brothers John and Bryan who are supported by their sister Andrea and brother Colin.
The company has two production locations. The Westdale location, measuring more than 17,000 m2, focuses on the production of mini gerberas, gerbera and spray chrysanthemums. The Grimsby location, measuring almost 11,000 m2, produces gerberas.
No production without growth
Various varieties of gerbera at the Grimsby location were severely affected by mealy bug, with the Tess variety being the hardest hit. Following a meeting with consultant Paul Kelley from Koppert Canada and consultant Erik van Santen from Koppert Nederland, Van Geest decided to combat the pest for a second year in a row with Cryptobug, the predatory beetle Cryptolaemus montrouzieri.
The beetle was released a number of times as of week 13 (28 March), a time at which there were particularly high levels of mealy bug. Growth had come to a standstill and the crop affected was not producing any flowers.
'The crop was still home to some Cryptolaemus beetles from the previous year. Thanks to this, we were able to work according to more or less normal release numbers,' explains Erik van Santen.
Mealy bug down by 20%
Two weeks later, in week 15 (11 April), the levels of mealy bug had decreased by 20%. Five to twelve predatory beetle specimens were counted on each plant. Half of the plants were showing some signs of growth again.
Mealy bug down by 40%
In week 17 (25 April), the levels of mealy bug were 40% lower. Production started again, with on average five to seven predatory beetle specimens present on each plant and no mealy bug identified on the new parts of the plants. Three quarters of the plants were growing again.
Mealy bug down by 70%
The numbers of mealy bug had decreased dramatically by week 20 (16 May), with a 70% lower level than six weeks earlier. Three to six Cryptobug specimens were counted on each plant. The crops were producing; three quarters of the plants were growing; and no mealy bugs were identified on new parts of the plant.
Mealy bug down by 90%
Three weeks later, in week 23 (6 June), the levels of mealy bug had decreased by no less than 90%. Only a few plants had not survived the mealy bug infestations, and the rest of the plants were entirely back in production. One to three predatory beetles were counted on each plant.
Chemicals: a vicious circle
Erik van Santen clarifies, 'Mealy bug is a problem in various crops. This pest is very difficult to combat with chemical crop protection agents in perennial ornamental crops, especially when the crop is thick, as this provides the mealy bug with ample hiding places. Chemical crop protection agents are not an option, as they upset the natural balance, giving scope for other pests to cause problems. This means that mealy bugs can always return. It's a vicious circle.'
Efficient and effective
The approach chosen by Van Geest Bros. Limited is the better one, thinks Erik. 'It is rather spectacular how a level of infestation can be brought back by ninety percent in ten weeks' time. This is proof yet again of how efficiently and effectively good beneficials work. Of course, an important advantage of this approach is that it does not damage other beneficials and therefore does nothing to upset the natural system as a whole. Growing at Van Geest Bros. Limited has become much more secure.'