What are the symptoms of soft rot in clivia?
Clivia, also known as sword-leaf bush lily, large-leaf bush lily, and Damulan, is a fairly common flowering plant and a variety that many flower enthusiasts greatly favor. However, in the hot summer, clivia is very prone to disease, and soft rot is one of the easier diseases to occur in clivia in summer.
Clivia
Soft rot mainly harms the pseudobulbs and leaves of clivia. In the early stage of the disease, the leaves are affected: the heart leaf and the base of the heart leaf show dark green water-soaked lesions, the diseased leaves rot, soften and droop, and the disease spreads to the root system, turning it mushy, the leaf heart falls off, and the whole plant dies. The pathogen of soft rot is Erwinia. The lesion first rots from the base of the plant, then the leaves begin to rot; the leaves and stems rot into a mushy state with a foul odor. After 2-3 d, the diseased part of the leaf shows a slimy, soft-rot "stem rot type" lesion. There is the type in which the outer leaves remain good while the heart leaf rots; there is the type in which the leaf and stem base remain good while the leaf partially rots, with the entire leaf completely rotting within 12 h and gradually spreading to its adjacent leaves, the diseased part showing a water-soaked "leaf rot type" lesion; and there is also the "root rot type" lesion, with rotting roots, wilting leaves, and a pus-oozing root system. The soft rot pathogen mainly overwinters in diseased plant residues and in the soil. In summer, rainy and humid weather, high temperatures, poor ventilation, and the application of large amounts of undecomposed fertilizer all make the disease more likely to occur.
Control of soft rot in clivia
Clivia soft rot is also known as clivia bacterial soft rot and clivia rhizome rot. It is a common disease of clivia and occurs in cultivation areas in both southern and northern China. When the disease occurs, it often causes the leaves to become soft-rotted, spreading downward to the stem; in mild cases it affects the ornamental value, and in severe cases the whole plant collapses.
Symptoms: It mainly harms the leaves, stems, and roots of clivia. In the early stage of the disease, water-soaked dark green lesions appear on the leaves, gradually expanding and spreading; the diseased tissue becomes brown and soft-rotted, with a clear boundary from the healthy tissue. In the later stage, the diseased part dries up and sinks. In severe cases, the entire leaf becomes soft-rotted and droops, separating from the stem. When the stem is infected, it spreads upward to the leaf base and downward to the roots, causing the roots to rot, the whole plant to wither and die, and the soft-rotted leaves to fall off. Disease pattern: The pathogen is Erwinia carotovora. The bacteria survive and overwinter with diseased plant residues, and are spread by rainwater, irrigation water, and insects, mostly invading the plant through wounds. After invading, the bacteria secrete pectinase to dissolve the middle lamella, causing cells to rupture and cell fluid to overflow, forming soft rot. The bacteria develop at temperatures of 2-40°C, with an optimum of 25-30°C. In summer, high temperature, high humidity, poor ventilation in the facility, numerous plant wounds, and severe damage by scale insects make the disease more likely to occur and cause severe damage.
Control methods:
(1) Strengthen management. Be careful to water from the edge of the pot, and never let water get into the heart leaf. If water is accidentally poured into the heart leaf, use absorbent cotton to dab up the accumulated water in the heart leaf. Pay attention to ventilation in the facility, and control pests such as scale insects in time. When transplanting or repotting, prevent bending or bumping the leaves and stems and causing wounds.
(2) When the disease is mild, cut off the diseased leaves and spray the whole plant with a pesticide. Options include: 50% copper bis(dodecylbenzenesulfonate) wettable powder at 500 times dilution, 72% agricultural streptomycin sulfate soluble powder at 4000 times dilution, 77% Kocide wettable microgranule powder at 500 times dilution, 47% Kasumin wettable powder at 800-1000 times dilution, etc. Spray once every 10 days, for 2-3 consecutive sprays.
(3) When the disease on the leaves is relatively severe but the roots and stems have not rotted, or only a few roots have rotted, pull up the diseased plant together with its roots, cut off the diseased leaves and diseased roots, wash off the soil with clean water, then soak in 0.1% potassium permanganate solution for 5 minutes, rinse again with clean water, place it with the roots facing up in sunlight for 30 minutes, and then air-dry for 4-5 days. The flower pot and potting soil must be sterilized at high temperature; after they have cooled thoroughly, pot the plant, or discard the original soil, prepare new sterile soil, and use a new pot for planting. When planting, do not bury it too deep; water thoroughly and place it in a cool place. After 10-15 days of recovery, new leaves will grow.
(4) If the disease is severe and the roots and stems have completely rotted or mostly rotted, remove them promptly and disinfect the soil by spreading quicklime, etc. If it is a potted plant, the flower pot should be disinfected, the soil should be discarded, and new soil should be used instead.
Control methods for clivia soft rot
Clivia belongs to the genus Clivia in the Amaryllidaceae family and is a perennial evergreen herbaceous flower. Since it was introduced into China from Japan in 1932, it has been commonly cultivated and planted in various regions of China. Clivia soft rot is a common disease of clivia, and after it occurs, it often causes the whole plant to die and thus causes considerable economic loss. For disease control in clivia, targeted measures need to be taken for prevention and treatment according to the characteristics of its symptoms.
I. Symptoms
Soft rot mainly harms the pseudobulbs and leaves of clivia. In the early stage of disease at the stem base, small water-soaked spots appear, then gradually enlarge into light brown spots and spread to the pseudobulb, causing its tissue to rot and become soft-rotted with a foul odor. The lesion at the stem base can also spread along the leaf veins to the leaves. In the early stage, the leaves show water-soaked spots, which then rapidly enlarge and become rotten and semi-transparent, with a yellow halo around the lesion and a broad band around the halo. In severe cases, the entire leaf rots and disintegrates into a wet rot.
The pathogen of this disease is bacteria, mainly Erwinia chrysanthemi and the blackleg pathovar of Erwinia carotovora of the genus Erwinia.
II. Disease pattern
The pathogenic bacteria overwinter in the soil or in diseased plant residues. The disease can occur from June to November, but mostly occurs during periods of high temperature and high humidity in summer; poor ventilation favors the spread and development of the disease. The bacteria can survive in the soil for several months, and diseased soil is an important source of infection. Therefore, incomplete soil disinfection can easily lead to the occurrence of this disease. In addition, it can also be spread by water flow, insects, contact and friction between diseased leaves and healthy leaves, or through tools used in operations. The bacteria invade the plant through wounds and can cause disease within a few days, and can repeatedly infect during the growing season. In summer, if the stem heart of clivia is exposed to rain or if water is carelessly poured into the stem heart, this disease can be induced. Besides infecting clivia, this pathogen can also cause disease in chrysanthemum, dianthus, dahlia, begonia, and Rohdea japonica, etc.
III. Control methods
1. Soil disinfection: In order to prevent soft rot early, disinfect the potting soil before transplanting. The soil can be disinfected with 0.5%-1% formalin, about 10 g per sq m; it can also be disinfected with chloropicrin at 60-120 g/sq m or 70% quintozene at 8-10 g/sq m.
Used flower pots and contaminated tools should also be cleaned and disinfected with 1% copper sulfate before use. Usually, do not water too much, so as to avoid the potting soil becoming too wet.
2. Agricultural control: Cut off or pull out diseased plants in time and destroy them; do not bruise the plants when planting or transplanting, so as to avoid wound infection; during the disease period, pay attention to drainage so as to keep the rhizome dry and avoid rotting of the roots, rhizomes, and bulbs.
3. Chemical control: After the disease occurs, spraying agricultural streptomycin at 1000 times dilution or Bordeaux mixture at 150-200 times dilution about once every month can control the spread of the disease. At the same time, when pests are found, control them in time to reduce wounds and lower the incidence of the disease.