In the survey of dragon fruit (Hylocereus spp.) orchards, it was found that the fruit is sensitive to diseases like stem and root canker, anthracnose, stem rot and leaf spots etc. In this article, relevant information about the major diseases and possible management of dragon fruit has been presented.
1. Stem and Root Canker:
Generally, the infection of this disease was found to be high in orchard with poor crop management practices. Additionally, the disease is a major problem in many dragon fruit-producing countries. It poses a significant threat to yield and fruit quality in cultivating dragon fruit. It is caused by a fungus called Neoscytalidium dimidiatum
Symptoms: In the initial symptoms appear as dark, yellow, small spots are seen on the affected areas, in which red spots are mixed. As the disease progresses, the centers of these spots become elevated and colour changes from red to gray. The shape of the center of each spot changes into balls. Black-colored Pycnidia are formed in each spot. Pycnidia contain the spores of the fungus. As the disease progresses, yellowing of the affected branches and rotting of the leaves occurs. Later the dead tissues are separated from the healthy tissues from this on holes are visible. On the affected area yellow, dark stains are visible and such affected fruits rot immediately. Puffed peels several times but due to the prevalence of Pycnidia on the peels gives a thick black color.
Favorable conditions: The disease is prevalent in orchard throughout the year. But its symptoms are more in the rainy season due to pycnidia pycnidiospores (fungal spores) come out and spread by rain splashes. The disease survives in temperature range from 20 to 40°C. But at 35-370 C of temperature the disease severity is more.
2. Anthracnose
It is also found in the rainy season. The disease appears during flowering and fruiting time as a result deteriorates the fruit quality and hampers fruit production. Colletotrichum species are commonly responsible for anthracnose. Among these Colletotrichum ghasidas, Colletotrichum siamense, Colletotrichum enigma and colletotrichum truncatum etc. include powdery mildew as well.
Symptoms: This disease symptom appears on fruits and branches of dragon fruit. In early symptoms, diseased branches are orange to brown in color small dark spots, as if soaked in water and spots are visible. A yellow border around the spots is visible over time these size of the spots increases and there patches of dead tissue appear. In these black colour acervuli are visible. It contains powdery mildew spore. On fruits, small, light brown spots blisters appear, it turns to water-soaked patches, among these visible black coloured acervuli in circular perimeters are visible. Thus of polluted puffs induce favorable conditions during storage of fruit and causes rapidly rotting.
Favorable conditions: The biggest impact of this disease and its spread is mainly during high humidity, hot temperatures and frequent drizzle occurs during the rainy season.
3. Stem Rot
In dragon fruit bacterial and fungal are two pathogens that causes stem rot. Apart from these sometimes bacteria in chronic infected areas and combined infection of both fungi is also seen. Stem rot, usually caused by bacterium Xanthomonas erwinia and Enterobacter species and caused by fungi Fusarium species are responsible.
Symptoms: In infected fruit, the stem infected by the bacterial soft rot appears yellow to brown water-soaked lesions. The length of the small lesions increases and turn into large patches. Affected tissues produce a foul smell. These fruits infected with the disease rotten completely within three days. Fusarium stem rot is also called basal rot. The initial symptoms of this disease include., Brown lesions in the lower part of the fruit stem. These brown spots will appear gradually the fungus spreads to the upper parts of the body and infects the leaves becomes soft and yellow and rot eventually. During dragon fruit nursery production improper cuttings, hardening and without use of fungicide treatment causes problem of bacterial rot which later spread in large-scale areas.
Favorable conditions: In months of October and January, fluctuation in the day and night temperature causes disease intensity. Heavy irrigation after a long drought causes an outbreak of this disease. Infected soil and planting material increase the spread of disease.
Integrated disease management
For proper management of dragon fruit, the disease prevention in initial periods and factors causing disease should be arranged properly. Dragon fruit plantation and nursery conditions must be clean and sorted by paying time to time attention.
Selection of planting material
For disease free nursery production, healthy seedlings for planting material should be used. Hardening of planting material should be done for 7-10 days in shade and after that treat with Carbendazim @0.1% and Copper oxychloride @0.25% and Mancozeb @0.25% is necessary.
Orchard cleaning and plantation distance
Sorting out infected plants and these plants must be destroyed. If infected plants left remains in the orchard then the pathogen spores spread in the whole of the orchard. After sorting immediately apply 1% Bordeaux mixture it helps in prevention of disease. The equipment used for sorting should be disinfecting by immersing in copper oxychloride @0.25% solution. In an orchard maintaining optimum distance between plants provides adequate ventilation and light. This reduces the spreading of pests and diseases.
Management with fungicides
Depending on weather and field conditions the fungicide spray concentration should prepared. Various activities in the spray of fungicides and the number should be increased according to their efficacy. For example, Powdery mildew spray-grade dust protection doses such as Mancozeb @0.25%, Copper oxychloride @0.25% and other remedial fungicides such as difenoconazole + azoxystrobin @0.1% can be used.