Informing, advising and debating in order to improve the quality productivity of our floriculture sector in the region. That is the aim of Floriculture Magazine. With new molecules been registered into the country yearly and the agrochemical market in full swing, growers are taking a renewed interest in crop protection. To quench your thirst on safe and effective use of agrochemicals, meet our professional correspodent. In this issue she has picked a key area and will talk direct to the people who draw spray programs in your farms.

Briefly discuss the choice of a good, safe and effective insecticide in a spray program.
Be sure to use suitable chemicals rather than just familiar ones. When choosing a chemical several factors are important – not just price alone. Is it effective against that pest/disease? Its mode of action? WHO classification? MPS/Kenya flower council coding? Will the with-holding period or other safety issues fit with your harvesting schedule? Can it cause any damage to the crop? Will it kill beneficial insects you are trying to protect? Do you know how to use the chemical to its full effectiveness? Do you have the right equipment and application methods for that chemical? Is it legal to use it on your crop?

How do you handle the different chemical groups?
Rotate products basing on chemical group / target sites in case in the same chemical group but no cross resistance known. Check with FRAC /IRAC the comments on resistance (High, medium or Low resistance risk). Rotation of the Chemical Groups should be done every 2-3 sprays. This will manage the threat of insecticide resistance. These procedures will help to reduce the risk of increasing the level of resistant insects in the pest populations. You must have a chemical group rotation plan which you must follow religiously. You must also ensure that the chemical is correctly mixed and used under the right conditions (additives (+/-), temperature, pest threshold level etc.). When spraying, Make sure that you get good coverage to get the maximum kill and do not spray more often than you need to. Spray interval range from 3-7 days depending on the level of infection and infestation which is a function of weather.

When do you spray?
The grower must spray when Pest/Disease pressure is not too high. In this case, you must follow all requirements of effective insecticide application, taking careful note of the different application requirements of some chemicals. Crop monitoring and insect scouting will inform you when the pests have reached a level where spraying is required. To reap maximum profit, the grower must follow the requirements of effective insecticide application. The grower must select an insecticide from the right chemical group according to the chemical rotation plan.

When spraying one should follow all important legal and safety requirements (e.g. protective gear, re-entry time and with-holding period from spray to next pick).

For maximum benefits the grower should examine and closely follow all guidelines for effective use of the chemical (e.g. use of a wetting agent if required, avoidance of high temperatures etc.), ensure mixing of the correct rate and volume for the crop and pest. One should avoid using any other additives in the tank mix unless certain that it is a safe and effective combination. Application must be done promptly and at the best time of day for a good kill - usually morning or late afternoon. Head of sprays must check pH of the mixture before adding the chemical to make sure it is between 6.0 and 8.0 (6.5 is best) and also find out how long it should take the chemical to work (minutes or days).

The grower must apply the chemical to achieve good coverage by making sure the spray equipment is calibrated to deliver the correct volume for the crop area and growth stage and that the jets and pressure setting are delivering the right droplet size and penetration to get good coverage The movement of the spray nozzles must achieve good coverage from top to bottom, between plants and under leaves. The sprayer must avoid run off with most chemicals as this often leads to leaf burn and can actually leave less chemical on the leaf for insects! General rule is from 6.30 to 10 am and 2 to 3.30 pm depending on the weather condition. Make sure there is ample time for crop foliage to dry before night to avoid outbreak of foliar diseases. Thrips ,caterpillars,aphids should be sprayed between 8-10.30 when they are active.

What should I consider when spraying?
Grower must take into consideration the weather Pattern. Disease /Pest Cycles are a times linked to the ecological prevailing weather conditions. Incorporation of protective measures is a key factor to delay or lower the Disease/Insect pressures. Cultural Practices should also be incorporated like proper Hygiene, crop rotation etc. Target pest/disease and Spray Volume is a key factor. Spray volume/Crop canopy ie: 3000lit mites, 1500lit Powdery Mildew, 800lit Botrytis,1500lit Downy Mildew, Insects 2000-2500lit/Ha. The grower should also consider drift effect. In case you are spraying Herbicides make sure that the adjacent crops are safe to avoid damage.

What precautions should I take after spraying?
The grower must check plants after spraying to confirm the effectiveness of the spray application. This is done by comparing before and after spray pest numbers. You also need to check fruit, leaves and flowers for a comparison of pest numbers in 1-3 days depending on how long the chemical takes to work. Then finally check sticky traps twice over the next week for pest build up (at 2 and 5 days). Re-entry interval is also a key element.