Field Operation Management and Disease Prevention and Control Techniques for Flowers

When many flower growers hear the words "disease prevention and control," they think only of "spraying chemicals" (pesticides), "what chemical to spray," "how many caps, how many spoons." However, chemical control is only one method of disease prevention and control. If field operation management is improper, relying solely on spraying fungicides cannot economically and effectively control diseases. Flowers are crops with relatively high economic value, and their cultivation philosophy should also advance accordingly. In the comprehensive management cultivation model, disease management is one link among others, but it is not an independent link. One cannot manage operations with the mindset that spraying chemicals whenever disease appears is all that is needed. Only comprehensive management capability can achieve integrated control of flower diseases.

Causes

Diseases caused by non-living factors are called non-infectious diseases because they do not infect one another, also known as physiological diseases. Diseases caused by pathogenic organisms such as fungi and bacteria are infectious and are called infectious diseases.

Causes of physiological diseases

Unsuitable temperature, unsuitable light, water imbalance, unsuitable nutritional conditions, excessive soil salinity, harmful gases and substances, unsuitable soil pH, and so on can all affect the normal growth and development of flowers and lead to disease. From this it can be seen that physiological diseases cannot be effectively controlled by "spraying chemicals."

Causes of infectious diseases

The pathogenic organisms that cause flower diseases include fungi, bacteria, viruses, nematodes, mycoplasma-like organisms, viroids, parasitic seed plants, and so on. Whether these pathogenic organisms harm flowers and the degree of harm depends on the pathogenic organisms, the flowers themselves, and external environmental conditions. From this it can be seen that relying solely on "spraying chemicals" also cannot completely control infectious diseases.

Disease only occurs and spreads when pathogenic organisms, susceptible flowers, and a suitable environment exist at the same time. If a greenhouse contains susceptible flowers and pathogenic organisms but lacks environmental conditions suitable for disease development, disease will not appear. Therefore, the basic strategy of disease prevention and control is how to break this triangular relationship so that the three cannot appear simultaneously in the cultivation greenhouse, such as reducing the density of pathogenic organisms or even completely eliminating them, planting disease-resistant varieties, and changing the cultivation environment.

The impact of field operation management on disease prevention and control

Greenhouse management

Anthracnose, bacterial diseases, and others often occur in high-temperature and high-humidity environments, while gray mold occurs under cool, moist climates, and powdery mildew is more likely to occur in facility cultivation with poor ventilation. Therefore, the regulation and control of environmental factors such as temperature, relative humidity, ventilation, light, soil moisture, and pH value in the cultivation greenhouse is particularly important for disease prevention and control.

Regularly maintaining ventilation and light transmission in the greenhouse is an extremely important external condition for suppressing disease occurrence. Even in severe cold winter, the side film should be lifted or windows opened at noon every day to reduce humidity inside the greenhouse and on the plant surface. Otherwise, by March, diseases will be induced on a large scale, such as eye spot disease and leaf spot disease of carnation, and gray mold of gerbera.

Low light intensity causes excessive plant growth and makes plants more susceptible to disease. Shading in summer avoids damage from strong light, but excessive shading makes flower stems softer. Light intensity should be controlled at a level suitable for plant growth and development.

Plant management

Wounds caused by transplanting, pinching, and so on can all become entry points for pathogens. Pinching should be done on sunny days as much as possible to help wounds heal and avoid invasion by pathogenic bacteria. When carrying out cultivation operations such as pinching and cuttings, tools should be disinfected regularly, and transmission of pathogens through fingers and tools should be avoided as much as possible.

Reasonably adjusting plant and row spacing can effectively reduce the occurrence of diseases.

Irrigation management

Drip irrigation, furrow irrigation, or water supply near the soil surface can effectively control disease occurrence by avoiding splashing irrigation water that carries pathogenic spores or bacteria onto healthy plants. Take care not to let water remain on petals or leaf surfaces. Even a very small amount of water is an important factor indispensable for the germination of most pathogenic bacteria, their invasion of plant tissues, and their reproduction. Furthermore, when encountering scorching sun and high temperatures, it can also easily cause scorching.

Soil moisture that is too high causes the oxygen content in the soil to decrease and the carbon dioxide concentration to rise, increasing damage to roots by root rot pathogens, while soil moisture that is too low makes seedling damping-off caused by Rhizoctonia more severe. In addition, off-ground cultivation is also a cultivation method for avoiding the occurrence of Phytophthora disease.

Fertilization management

Plant growth requires nutrients, but applying too much fertilizer instead harms the plants. Problems such as yellowing of plants and poor growth caused by excessively high EC values and fertilizer burn are also often seen. The choice of fertilizer type must vary according to the flower variety; different flower varieties have different nutrient requirements. The strength or weakness of plant vigor also affects the probability of disease occurrence.

Sanitation management

Field sanitation can be said to be the easiest and most effective control measure. Removing diseased plants, diseased leaves, and weeds and carrying them away from the cultivation site for destruction can reduce or even completely eliminate the density of pathogenic bacteria at the site. Plant residues must not be piled up somewhere at the base and left to rot, because these residues will become a breeding ground for pathogens, spread by wind and splashing, and increase the chance of healthy plants becoming infected.

For systemic diseases such as bacterial diseases, viral diseases, or wilt diseases, once the pathogen invades the plant body, it is not easy to control. Infected plants should be pulled out entirely as early as possible (together with the soil or substrate around the root zone) and carried away from the cultivation site for destruction so as to avoid the spread of disease. If only the branches and leaves showing symptoms are pruned away, not only can the goal of suppressing spread not be achieved, but the pathogen may spread to nearby healthy plants through pruning tools or root-to-root contact, invisibly turning the pruning work of eliminating diseased tissue into inoculation work for pathogenic bacteria and instead accelerating the spread of disease. Moreover, a clean and tidy cultivation environment is not only easy to manage but also looks refreshing and pleasant.