Effectiveness of alkaline fertilizer on the control of banana Fusarium wilt and regulation of soil acidity in banana orchard

【Objectives】Soil acidification, nutrient imbalance, frequent occurrence of Fusarium oxysporum f. sp. cubense in banana plantation are the main reasons leading to the serious decrease of banana production and even the constrained abandon of banana orchard in many regions of China. On the base of long term research, a alkaline fertilizer (AF) special for banana was make out, and its effect on regulating soil pH and the control of Fusarium wilt was investigated in a three years field experiment in Hainan, so as to develop a cost effective measure to improve soil pH, decline incidence of the Fusarium wilt and increase banana production.【Methods】A complete random design field experiment with five-factor was conducted and the effect of alkaline fertilizer (AF) on soil acidity, incidence of the Fusarium oxysporum f. sp. cubense and banana yield was compared with conventional fertilizer (CCF) for three years in Wanzhong banana plantation district of Ledong County, Hainan Island Province. Each banana plant was applied with 200 g of N, 80 g of P2O5 and 400 g of K2O. There were five treatments： alkaline fertilizer (AF) + controlled release fertilizer (CRF) + conventional fertilizer (CCF), AF + CRF, AF + CCF, CRF + CCF, CCF respectively, each treatment had three replications. 0-15 cm depth soil samples were collected in 60 cm away from the pseudo stem in the bud formation stage, pumping stage, fruit enlargement stage and banana harvest period, respectively.【Results】 1) Both the disease incidence and index of the Fusarium oxysporum f. sp. cubense were negatively correlated with the soil pH value (P0.01) significantly, which meant the incidence of the Fusarium oxysporum f. sp. cubense was worse in soils with lower pH. The rate of yellow leaf showed significant or extremely significant positive correlation with disease incidence and index as well, in other words, higher disease incidence and index lead to larger number of yellow leaves, and less green leaves consequently. 2) The alkali fertilizer could increase soil pH significantly and keep the soil pH in range of 7.0 to 7.4. The disease incidence and disease index of Fusarium oxysporum f. sp. cubense at each key growing stage of the banana were remarkably lower than controlled fertilizer. The disease incidence and disease index were as high as 62% and 21% in control, while those were only 18% and 5% in the AF treatment, respectively. 3) The harvest rate of banana fruit increased from 56% with the control to 72% with the AF treatment. The harvested yield of the AF treatment increased by 13267 kg/ha, being 156% of the control. 【Conclusions】Application of AF can maintain favorate soil conditions for banana growth through regulate the soil pH in rang of neutral and weak alkaline range, and decline the rate of yellow leaf and increase the single plant yield and the harvest index. Therefore, the use of alkaline fertilizer is a cost effective measure to regulate soil pH value, keep equilibrium of nutrients, resist the infection of Fusarium oxysporum f. sp. cubense during banana growth, thus achieve a high yield of banana.