Effective pest control is an essential part of modern food production. Different pesticide products, like herbicides, fungicides, and insecticides, are used to ensure healthy growth of the crop and efficient land use. In addition to the active ingredient in the pesticide, auxiliary components can be added to the pesticide formulation or separately to the spray tank. These auxiliary elements are also called adjuvants, and they are used to ensure the effect of pesticides in different environmental conditions. Typically adjuvants can improve the biological activity of the herbicides by, for instance, reducing spray drift, increasing the wetting of the plant surface or enhancing the uptake of the herbicide into the plant leaves. Let me present two cases where microfibrillated cellulose (MFC) can help to improve the performance of pesticides.
IMPROVING THE UPTAKE OF THE HERBICIDE
Herbicides are used to control the weeds on the field. Microfibrillated cellulose can increase the efficacy of herbicides, as is shown in Figure 1. MFC improved the control of growth of a broad-leaf weed when glyphosate was used at a lower level than the label rate. This is believed to be related to the good water holding capacity of MFC. When the pesticide solution is sprayed on the plants, it stays as droplets on the leaves and the active ingredient can adsorb through the leaf cuticle into the plant. Also, MFC films are hygroscopic and can drag water from the surrounding environment. If the moisture stays longer on the leaf, the active ingredient has more time to adsorb and less of it is washed away from the target plant. MFC itself does not harm plants; it only helps the active ingredient to work as it should.
Figure 1. The fresh weight of black nightshade plants (solanum nigrum) 14 days after glyphosate treatment with and without MFC (Exilva, Borregaard). The weight is compared to that of untreated weeds (%). The glyphosate dosage (0.6 mM) was below the label rate. MFC improves the efficacy of glyphosate against the weed growth.
Figure 2. Plants (black nightshade) treated with 0.6 mM glyphosate (A) and with 0.6 mM glyphosate + 0.01% MFC (Exilva, Borregaard) (B) 2 weeks after the treatment. MFC enhances the effect of glyphosate and reduces the growth of the weed more than the reduced rate of glyphosate alone.
Better control of the plant disease caused by fungi
Fungicides are another group of pesticides which is applied by spraying (foliar application). Fungicides protect the plants against diseases caused by fungi. As Figure 3 shows, MFC can also improve the efficacy of a fungicide product called propiconazole. Even if more research is needed on this topic, it seems obvious that MFC can boost the effect of different pesticide products.
Figure 3. The number of leaf spots on impatiens plants 30 days after spores of Alternaria alternate were applied compared to untreated plants (reference). Afterwards, some of the plants were treated with propiconazole (Banner Maxx, Syngenta) or propiconazole and MFC (Exilva, Borregaard). Adding MFC to the treatment solution improved the efficacy of propiconazole against the pathogen.
Figure 4. The brown spots on the leaves are caused by a pathogen Alternaria alternata.
Efficient farming and food production are important topics when the population on the Earth is growing. At the same time, the agriculture has to be safe to human beings and the environment. MFC is a safe, bio-based product which can improve the efficacy of pesticides and in that way reduce the chemicals used in farming.