The use of supplementary lighting and higher plant densities has led to a dramatic increase in pest pressures for Dutch chrysanthemum growers. Certis Europe has been working to help them not only to improve control of their major pests, but also to increase their profits.
A combination of factors in the production of cut chrysanthemums has resulted in pest control problems for growers. The trend to plant at higher density has made it increasingly difficult to get good spray coverage among the plants. This, combined with the use of supplementary lighting, which has caused dramatic increases in pest pressure, has created a situation where pest control has been disappointing. The growers’ first response, to increase spray frequency, did not solve the pest problem and has, inevitably, increased costs as well as contributing to problems of resistance with red spider mite. Damage to flowers from red spider mite resulted in lower price per stem and thrips problems caused yield reduction as well as flower damage, which also resulted in reduced price per stem. Biological control programmes were not always reliable and chemical control programmes ineffective so it was clear that a new approach was required.
The IPM programmes:
Certis Europe set up trials with a grower to compare the use of three different programmes of biological controls with a conventional programme. The programmes all included Phytoseiulus against red spider mite and, for thrip control, compared
Other pests were controlled with selective or short persistence pesticides. Initially growers were sceptical about the use of beneficial insects, particularly as the cropping cycle for cut chrysanthemums is so short – just eleven weeks, but after three years of IPM trials, the success of the IPM programmes is changing grower perceptions and many are now using, or at least experimenting with, the new strategies.
In a new crop cycle, the programme is launched with the use of CleanStart, a range of soil fumigant products to ensure clean conditions for the new crop. At the same time beneficials can be released into the crop, including Phytosure, containing Phytoseiulus persimilis to target spider mites. The Mite-y applicator was used in one of the programmes using Botanigard to further reduce labour costs. The manual introduction of Phytoseiulus to crops such as cut chrysanthemums is particularly time consuming, typically taking two operatives 20 minutes per bay. By automating the process using the applicator a single operator can achieve the operation in just five minutes. The Phytosure applicator was developed, in conjunction with BCP, at Jan Kreling, a 12 ha cut chrysanthemum nursery in Bruchem. To further improve efficacy of the Phytosure applicator, BCP has developed a smaller 1K Phytosure unit.
For thrips Amblyseius cucumeris was used in the form of Ambsure (abs) long life breeder packs. The sachets are constructed of water repellent material and stood up well to overhead watering, remaining firmly attached to the crop wires. Six weeks after introduction, they remained highly productive, releasing large numbers of predators and playing a valuable role in keeping thrips populations under control.
The three trials were run side by side.
It became apparent from the initial trials that Phytosure provided significantly better control of red spider mite than the available pesticides. In addition all three of the trials gave effective control for thrips. The costs of control were different in each case but all were higher than the conventional controls. However, other benefits outweighed the actual costs and the crop was definitely of superior quality using the IPM programmes.
Benefits to growers
The benefits were calculated by comparing the overall return of a conventional programme, a competitor IPM programme using ABS and the Certis programme using Botanigard. Standard chrysanthemum operating margins were taken (Kwantitatieve Informatie voor de Glastuinbouw) and then adjusted in line with the changes in crop quality and inputs used (information provided by DLV Plant). The following assumptions were used:
Grower costs and margins per 1000 sq.m. of chrysanthemum crop:
|Conventional||IPM with |
|IPM with |
Botanigard and Mite-y applicator
|Crop price €||11,000||11,250||11,250||11,250|
|Crop protection costs €||272||427||295||286|
|Othering operating costs||7,600||7,600||7,600||7,600|
Growers have confirmed the superior quality of the flowers treated by IPM compared to those treated conventionally. As a consequence there are clear financial benefits for growers
Certis NL and BCP are continuing to work closely with growers to develop further new pest control strategies.