Effect of Silicon Sources on Sugarcane Orange Rust, Ring Spot and Red Rot in Brazil

Brazil is the world’s largest producer of sugarcane (Saccharum officinarum), but the occurrence and severity of diseases such as orange rust (Puccinia kuehnii), ring spot (Leptosphaeria sacchari), and red rot (Colletotrichum falcatum) could be part of several factors limiting its production and is the reason for replacing cultivars. It is important to use other forms of disease control depending on the time required to obtain new resistant varieties. The use of silicon (Si) can provide more resistance to the plant making its less vulnerable to diseases. A study was conducted under greenhouse and field conditions. The greenhouse study had 13 treatments (control, fungicide, foliar solution I and II, K silicate, silicic acid at 20, 40 and 60 mg ha-1, wollastonite, agrosilicio, wollastonite + fungicide, wollastonite + K silicate; agrosilicio + fungicide; and agrosilicio + K silicate) with four replications. The field study had nine treatments (control, fungicide, foliar solution I and II, K silicate, silicic acid at 100 and 300 g ha-1 and phosphite at 0.5 and 1 L ha-1) and with three replications. Both studies used a randomized block design. The greenhouse study showed an increase in dry mass of pre-sprouted sugarcane seedling and Si uptake with foliar treatments, especially with silicic acid. K silicate and silicic acid showed lower severity of orange rust than the control and fungicide. On the field study silicic acid at 100 g ha-1 and 300 g ha-1 was more efficient in reducing the area under the disease progress curve (AUDPC) of ring spot compared to the control and K silicate. Fungicide was also more efficient in reducing AUDPC compared to the control as well.