Expert advice

Spray mixes – what you need to know

The increase in intensity of agrotechnical treatments conducted at plantations requires agricultural manufacturers to look for new solutions that would optimally permit the utilisation of each 'entry' of a field. One of the most frequently used optimisation treatments for plant protection products is their joint utilisation in mixes, referred to as 'tank mixes', permitting the execution of two or more treatments per run.

The use of a spray mix is, one the one hand, a gain in terms of time related to a reduced volume of entries of a field, translating as well to the division of labour on the farm, but this is also lower negative influence of the soil – as an unjustified increase of transit times can cause its excessive compaction and the destruction of its lumpy structure. The use of a tank mix permits one to utilise any short-term temperature optimum, thanks to which the treatment will be even more effective. An argument in favour of the use of spray mixes is also the fact of similar periods of the execution of individual treatments, e. g. fungicidal protection and leaf fertilisation. It is common to mix plant protection products between different groups and with leaf fertilisers. And even if recommendations of joint use may encompass the common application of fungicides, insecticides and leaf fertilisers, then tank mixes containing a herbicide and a leaf fertiliser are less popular.

Despite the multitude of rational arguments speaking for the use of tank mixes, one needs to remember that proven and tested compositions of agricultural chemicals may, as a result of an unfortunate turn of events, bring about unwanted results – a lack of effectiveness or difficulties in performing the treatment, and in extreme cases – lead to the destruction of the drop. Hence, deciding to use a spray mix, act with due care and great caution.

Before using a tank mix formulated on a farm for the first time, it is recommended to test its miscibility for a small volume, e. g. five to ten litres. For instance, if a pesticide is used in a dose of a litre per hectare, then for five litres of water, measure 25 ml – a syringe may come in handy for this purpose, it is significantly more difficult to measure solid forms of plant protection products and fertilisers. The order of addition of the individual components of the mix should be the same as in case of preparation of a tank mix. Such a mode of action will permit one to determine, whether the addition of the individual components does not negatively influence the physical properties of the spray mix – e. g. the formation of fibres or the like, formation of deposits or quick layer separation of the emulsion. We are sadly unable to check the influence of such a mix on the crop.

A suggestion concerning the possibility of use of plant protection resources together with each other and with leaf fertilisers may be obtained from a specialist consultant serving the farm, from the store, where we make purchases or from the label of the product. The label indicating use may also contain information concerning contraindications as to the mixing of individual products.

The preparation of the spray mix should be effected a shot while before the planned treatment, as physical and chemical processes taking place within the liquid stored by us exceeding the minimum need for this may negatively influence the effectiveness of the treatment or even limit the technical ability of its execution. It is also important to add the individual, relevant components of the tank mix in the correct order and with the hydraulic mixing unit turned on. The mix spray mix is created through the following nine steps.

Mieszaniny opryskowe
During the preparation of a tank mix using mineral fertilisers one must take into account their influence on the temperature of the solution. The addition of magnesium sulphate raises the temperature, which, in case of using well or system water for the treatment, the temperature of which is usually way below ambient temperature, is a favourable effect. The addition of urea, in turn, will reduce the temperature – this is frequently a negative effect. In such a situation, it is recommended to wait until the water temperature rises again.

On the one hand, a tank mix permits one to fuse plant protection products from various chemical groups, with the additional execution of leaf fertilisation; on the other hand, it permits one to broaden the spectrum of the controlled agriphages.

'Tank mix' – weed control

One of the most frequently recommended modes of control of weed is to fuse with one another several products utilising diverse active ingredients in order to control as broad a spectrum of weed as possible. One needs to take into account that the purpose of such actions should be the achievement of a controlled weed spectrum that is not guaranteed by any other available product. A typical spray mix used to control weed would contain products containing a windgrass control substance and components against dicots. In the autumn, a very popular partner for spray mixes is the active substance chlorotoluron (e. g. contained in the Opal 500 SC herbicide), which amends very well the action of other substances dedicated for the control of dicots. In spring, in turn, in order to control windgrass one can use, beside chlorotoluron, also other active ingredients such as e. g. pinoxaden, fenoxaprop-p-ethyl, sulfosulfuron. A further very good example of an active substance that is commonly used as a spray mix component is fluroxypyr; its advantage is very good effectiveness in the control of cleavers. Products containing this active ingredient may in the spring be mixed with products containing ingredients from the sulphurea group (e. g. tribenuron methyl) or with growth control products.

Spray mix and diseases

Even if herbicidal treatments in the growing season of crops are usually effected once, in specific cases up to two times, then control of diseases in crops is usually performed more than twice. Hence, it is necessary to assume a strategy in the process of countering diseases, and to plan ahead the protection programmes, which in addition need to be continuously verified depending on the health and condition of the plantation. In order to broaden the spectrum of controlled diseases and in order to introduce a further mechanism of action, it is reasonable in many cases to use, instead of using a one full dose solo, to reduce the dose and make a mix with other products containing active ingredients from various chemical groups. In case of fungicidal treatments in the farming of cereals and rape, the most popular active ingredient in spray mixes is tebuconazole. In practical farming, it is most commonly used in conjunction with chlorothalonil, azoxystrobin, prochloraz, methyl thiophanate, other triazoles and, depending on the needs, with other substances from diverse chemical groups.