The impact of climate change on diseases and pests of small grains and sunflowers in the Vojvodina region (Serbia)

Abstract

The risk of disease and pest damage to agricultural crops has increased significantly as a result of climatic changes. The climatic change has resulted in the dominance of pathogens that require higher temperatures for their development or are better able to adapt to drought conditions. This is the reason why the fungal diseases of the genus Fusarium and Septoria spp. that affect small grains have played a dominant role in causing significant damage and why the causal agents of sunflower spots develop very well and rapidly at high temperatures. The diseased plants may suffer from complete defoliation and premature ripening. Fungi of the genus Alternaria are favored by high temperatures accompanied by a short period of wet weather. The parasite develops best and most rapidly at temperatures between 20 and 30 °C. During the 2009 - 2010 growing season, there was a significant Fusarium infestation on wheat, barley and triticale in the Vojvodina region (Serbia). In the locality of Rimski Šancevi near Novi Sad, the percentage of Fusarium-damaged kernels in some commercial fields (the spring-planted variety Natasha) reached up to 33.3 % per m2. In the same growing season and locality, the levels of deoxynivalenol (DON) in cereal samples were very high. The effectiveness of the Pm resistance genes is correlated with the air temperature conditions. During the 1990 - 2009 period, numerous genotypes had the V7, V6 and V8virulence alleles. The most efficient among the sexual populations of the parasite was the gene combination Pm5+6 from the variety Coker 983. Compared with the previous period, the rust (Puccinia spp.) pathogens have recently formed fewer generations and have transitioned quickly from the uredo to the teleuto stage, which is a direct result of the climate change impact. Orobanche cumana is a serious problem in sunflowers. Since the 1990s, broomrape has caused significant damage to the susceptible hybrids in Serbia. In the north of the Backa region alone, 15 000 ha have been endangered. The yield losses depend on the intensity of the attack and can range from 5 to 100 %. Besides having a great impact on pathogens, the climate change also influences pests. Moths are insects and thus do not have a constant body temperature. The speed of their development is directly correlated to the air temperature. Increasing temperature leads to changes in the cycle of development and the diversity of the individual species. A species that we can safely say has become dominant due to the increase in air temperature is the cotton bollworm (Helicoverpa armigera). In years with mass outbreaks of the cotton bollworm in the north of Vojvodina, 60 to 100 % of maize ears and sunflower heads and 20 to 94 % of string bean pods were reportedly damaged.