Análise espaço temporal da ferrugem do cafeeiro e sua relação com o clima e a nutrição mineral com K e B

Abstract

The coffee rust (Hemileia vastatrix) is the main disease of this culture. The high coffee yields, density plantations, nutritional imbalance, drought, among others are responsible for the occurrence and progress of the disease. To minimize the damage of the disease and increase the productivity of coffee plants with sustainability is necessary to know the influencing factors such as water, light, nutrition and cultural management. In this context, the plant nutrition has the ability to increase or reduce susceptibility to diseases, interfering with histologic and morphological structures in tissue functions in virulence and the pathogen's ability to survive. Thus, there were three trials emphasizing the nutritional balance of nutrients B, K and P in the coffee rust management. Experiments were conducted in a greenhouse, in experimental plots and in large areas of irrigated production. The first trial aimed to evaluate the effect of K and B in the rust incidence and severity and dry weight of coffee seedlings in nutrient solution. The treatments consisted of 5 boron doses (0.05, 0.50, 1, 2 and 4 mg L-1 ) and 5 potassium doses (4.0, 5.0, 6.0, 7.0 and 8.0 mmol L-1 ). Positive interaction between nutrients potassium (K) and boron (B) affecting the intensity of coffee rust. From the dose of 1 mg L-1 B was an increase in coffee rust intensity with reducing the dry weight of seedlings. The second study aimed to evaluate the interaction between doses of K and B in the incidence of rust (H. vastatrix) of coffee in the experimental field. The experimental design was a randomized block design, with four doses of K (0, 100, 200 and 400 kg ha-1 K2O) and four of B (0, 1, 2 and 4 kg ha-1 B). For area under incidence progress curve (AACPDI) there was no significant interaction between doses of K and B. However, in foliar positive correlation was observed for nutrients K, B, Cu and Fe, which means increased coffee rust incidence with increased levels of these nutrients. This was due to nutritional imbalance in higher doses of K and B. In the third trial aimed to evaluate the spatial pattern of the relationship between rust and plant nutrition in irrigated coffee crop by center pivot. There was spatial dependence of coffee rust with P and K and B. The highest incidence of coffee rust occurs in areas with lower levels of P and K and the highest levels of B in leaves.