How to avoid rotten shoots? Mastering the right method is key

    As temperatures rise day by day, most orchid plants successively sprout new shoot tips - how delightful! But some new shoots, having grown only about 5-10 cm tall, develop reddish necrotic patches in their middle section, which gradually expand until the entire new shoot withers, scorches and turns black. What is the reason for this? 

(1) Non-infectious waterlogging damage. The bud sheath of an orchid tightly wraps the bud and leaves, making the base of the entire new shoot tip a closed, upward-facing tube shape. If excess water accumulates in this tubular leaf core, under conditions of insufficient light, lower temperatures and slow air movement, it is very difficult for it to evaporate completely; when it accumulates for a long time, waterlogging damage easily occurs. The new shoots of wild orchid plants often rot during the continuous spring rain season. Therefore, when we collect wild orchid seedlings, we often find withered and rotted shoot tips. So what are the factors that cause waterlogging damage in home-grown orchid shoots? 

(1) Orchid plants simply displayed outdoors with no rain shelter often have standing water in the leaf core during continuous spring rain; 

(2) For orchid seedlings displayed in greenhouses and polytunnels, water vapor from the ground rises to the roof, condenses, and drips into the leaf core of the new shoots. 

(3) Carelessness when watering and fertilizing causes water and fertilizer to be poured into the core of the new shoots; 

(4) When spraying pesticides and foliar fertilizers, the mist droplets are too large and the sprayed amount is too much, so the pesticide and fertilizer liquid flows into the core of the new leaves. 

(2) External force damage 

(1) Accidental injury during management processes such as division and repotting, collection and transport for sale, disinfection and planting, watering and fertilizing, and cutting off flower scapes and withered leaves;

 2. Damage caused by collisions from animals such as rats, cats and birds;

 3. Accidental injury from foreign objects. Although these external force injuries are not great, once injured, the already damaged

tissue is even more prone to waterlogging damage. 

(3) Infectious diseases. The main cause of orchid shoot rot is bacterial soft rot. This disease mostly occurs on the middle and lower leaves. The lesions initially appear yellow-green, water-soaked and translucent, and within three to five days turn brown and soft-rotted. The lesions are irregular in shape, with a clear boundary from healthy tissue, and putrid fluid flows out at the edges of the lesions. In the later stage the lesions dry out and sink, turning dark brown; in severe cases, the entire shoot tip rots and dries up. 

(4) Protective measures: 

(1) Waterlogging damage can be completely avoided as long as management is scientific. For example, for open-air orchid sites, bamboo strips should be used to build arches covered with plastic film to prevent rain damage; in polytunnels and orchid rooms, attention should be paid to air convection and exchange to prevent water droplets condensed on the roof from dripping into the core of the new shoots. That is, install exhaust fans, or set up windows and open them intermittently, to allow air convection and regulate the humidity inside the tunnel, keeping the orchid leaves at a moderate wet-dry level. When watering and fertilizing and spraying pesticides, the concentration should be moderate, the mist droplets should be fine, and it is best to spray from the underside of the leaves; at the same time, the amount should be appropriate, judged by the leaves not dripping. 

(2) For external force damage, management should be strengthened and operations performed carefully to avoid it as much as possible. 

(3) For infectious diseases, prevention is the priority.

 ①Pay attention to sanitation in the orchid site and its surroundings;

 ②Promptly remove withered leaves and spray insecticides to kill transmission vectors;

 3 Appropriately increase phosphate and potassium fertilizers, control the amount of nitrogen fertilizer, and pay attention to applying multiple trace elements, so as to increase the disease resistance of orchid plants;

 ④Do not use organic fertilizers that are not fully decomposed;

 ⑤Choose 600PPM streptomycin or oxytetracycline to spray the whole orchid plant, with special attention to spraying the pseudobulbs and new shoots; it is best to also spray the surroundings of the entire orchid site, the pathways, the orchid benches and the orchid pots. If it can be applied to the orchid soil, the effect will be even better. After the new shoots emerge, apply the medicine once a week for three or more consecutive times, and shoot rot can be avoided.