Key Points of Field Management Experience for Sugar Tangerines in October

1. Field management

① Orchard grass management: choose measures you consider economically effective to control weed growth. Controlling weeds at this stage helps expose the fruit to light, improves ventilation, reduces air humidity in the tangerine orchard, and supports disease prevention work.

② Strengthen late-stage nitrogen control of the fruit to ensure quality: citrus fruit quality is most affected by tree vigor at the late stage. When nitrogen is abundant and tree vigor is vigorous, most photosynthetic products are converted into nitrogen-containing organic matter and consumed by the growth of new shoots, while the fruit shows thick rind and large size, green peel, poor color change, low juice content, less soluble sugar, and poor quality. Regulatory measures: first, control the amount of nitrogen applied; second, topdressing should be applied early; supplemented by girdling, this is favorable for controlling tree vigor. If the above measures are poorly effective, then 60 days before the fruit ripens, apply organic matter with high carbon content into the soil (such as undecomposed straw stalks or a 2%-4% sugar solution applied at 5 liters per square meter of tree canopy) so that excess inorganic nitrogen in the soil is re-organified, inhibiting excessive nitrogen uptake by the root system before the fruit ripens, which helps lower the level of inorganic nitrogen in the soil and leaves, thereby promoting coloration, increasing sugar and reducing acid, ripening in a timely manner, and improving fruit quality.

2. Pest and disease control

The main pests harming sugar tangerines in October include red and yellow spider mites, rust mites, whiteflies, and fruit-piercing moths. In pest control, attention should be paid to the pre-harvest safety interval for pesticides. Generally, biological pesticides and physical lethal pesticides should be selected, such as abamectin + sulfur suspension concentrate to control the damage. In the later stage, sulfur suspension concentrate is used, which also has the effect of isolating pathogen infection and promoting fruit peel coloration. Thorough pest and disease control at this stage helps reduce storage rot losses.