Yield losses due to pests

Tanja Folnovic

Since the beginnings of agriculture about 10,000 years ago, farmers have had to compete with harmful organisms – pests. As with abiotic causes of crop losses, especially the lack or excess of water in the growth season, extreme temperatures, high or low irradiance and nutrient supply, biotic stressors have the poten tial to reduce crop production substantially. These organisms may be controlled by applying physical (cultivation, mechanical weeding etc.), biological (cultivar choice, crop rotation, antagonists, predators etc.) and chemical measures (pesticides). Crop protection has been developed for the prevention and control of crop losses due to pests in the field. Pests reduce crop productivity in various ways, classified by their impacts; stand reducers (damping-off pathogens), photosynthetic rate reducers (fungi, bacteria, viruses), leaf senescence accelerators (pathogens), light stealers (weeds, some pathogens), assimilate sappers (nematodes, pathogens, sucking arthropods), and tissue consumers (chewing animals, necrotrophic pathogens).


Abiotic and biotic factors causing crop losses

Without preventive protection with pesticides, natural enemies, host plant resistance and other nonchemical controls, 70% of crops could have been lost to pests. Weeds produced the highest potential loss (30%), with animal pests and pathogens being less important (losses of 23 and 17%). The efficacy of control of pathogens and animal pests only reaches 32 and 39 %, respectively, compared to almost 74 % for weed control. Beside losses caused by pests, about 15% of losses are caused by economic damage and a further 15% because of harmful biological diversity.


Efficacy of pest control worldwide in reducing loss caused by pathogens, viruses, animal pests and weeds.

The path to superior crop starts in the field, which means that every intervention in the field in greater or lesser extent will be reflected in the quality of the crop. Protection makes only 5-8% of the total cost during production in one vegetation. On the other hand, damages resulting from absence of proper care or poor performance can be huge. If all other interventions (fertilizing, weeding, tillage ...) are not performed properly, there will be a loss in the quality and quantity of farm yield. If protection is omitted or done superficially and inadequately, losses will be even higher. Activities which maintain crops in terms of growth potential and also help us in the fight against pests are: fertilization, pruning, weeding, loosening the soil, irrigation, removal of crop residues from fields, crop rotation, and other works of tillage. These principles control a number of animal pests and diseases, some of which are certainly the most dangerous: downy mildew, powdery mildew, leaf rust, blight, thrips.. Good agricultural practices which unite the full range of preventive measures are extremely important. When planting permanent crops, you should choose the best location, which should be sunny and airy, where dew/humidity does not retain for long. Sow/plant varieties resistant to most diseases, regularly suppress weeds, keep an eye on conditions favorable to the development of diseases and pests. Using software tools which can help you fight pests and diseases is also a must. The occurrence of most pests is caused by certain weather conditions; high humidity, low or high temperatures, rain, drought. Weather and temperature data are particularly helpful in following a pest's life cycle or in predicting how long it takes a certain pest to develop. Agrivi Farm Management Sofware knowledge base recognizes possible occurence of pests in your fields and alarms you 7 days in advance. Use this software to help you perform on time protection and reduce the risk of lower yield due to pests and diseases.

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