Everything you need to learn about controlling diseases of muskmelon.
1. Downy Mildew (Pseudopernospora Cubensis):
Generally, at initial stage small irregular yellowish lesions appear on leaves. Old lesions, which become necrotic, are clearly demarcated with light yellow areas. In high humid weather, faint, white downy fungus growth is observed on lower surface of leaves.
A downy mildew attack on muskmelon was reported by Bains and Jhooty (1976a), and Bains and Jhooty (1976b). Sohi (1984) observed this disease on different strains of muskmelon in almost all the states during the all India survey carried out in muskmelon growing areas.
i. The field should be well drained.
ii. Seeds may be sown at wider spacing.
iii. The disease can be effectively controlled by spraying Mancozeb @ 0.25% at 7 days interval.
iv. In severe conditions, Metalaxyl + Mancozeb @ 0.2% may be sprayed once.
v. Spray of copper oxychloride at 10 days interval also gives good control.
vi. Field sanitation is followed to reduce the inoculums by burning crop debris.
vii. The seed should be collected from disease free and healthy fruits to avoid the further infection.
2. Powdery Mildew (Sphaerotheca Fuliginea):
White long patches or coating appears first on the under surface of leaves, which later spread to both surfaces, stem, petiole and other succulent plant parts. Severe infection causes stunted growth and browning of leaves followed by premature defoliation. Usually the fruits of affected plants do not develop to maturity.
This disease is more severe under dry weather and favored by hot and humid weather, moderate temperature, reduced light intensity, and succulent plant growth. Good conidial germination is observed within a temperature range of 22-31°C with optimum at 28°C and low relative humidity of 20% for less than 2 hours. The disease is caused by Sphaerotheca fuliginea. The conidial stage has been noticed on Cucumis melo.
Control:
i. The spray of fungicides like penconazole 0.025-0.05%, tridemorph 0.05-0.1%, or carbendazim 0.1% at different intervals as per need commencing from first appearance of disease gives good control.
ii. All infected leaves should be collected and burned.
3. Gummy Stem Blight (Didymella Bryoniae and Phoma Cucurbitacearum):
This disease is now becoming severe in muskmelon. A watery scoop exudes from the nodal portion of the stem becoming yellowish brown gum after drying. Black dot like pycnidia is also observed on the affected bark. The fungus remains in/on seed and in soil both serving as primary source of infection. Fungus may survive up to two years in soil.
Control:
i. Use disease free healthy seeds.
ii. Follow long crop rotation with non-host crops.
iii. Plough the field deep in hot summer and follow Trichoderma application.
iv. Maintain proper drainage and aeration in the field.
v. Seed should be treated with carbendazim @ 0.25% followed by one drenching near collar region.
vi. Careful handling to avoid injury reduces risk of post-harvest rotting of fruits.
vii. Use of resistant or tolerant varieties reduces the risk.
4. Fusarium Wilt (Fusarium Oxysporum F. Sp. Moniliforme and Fusarium Solani):
The infection is both seed and soil born. This disease is more common in sandy soil. Symptom is characterized by yellowing in lower leaves, which gradually progresses on upper leaves. Immediately after infection, the plant starts drooping followed by wilting. Later on, wilting becomes permanent.
Characteristic symptom was observed as vascular browning after splitting of roots and lower portion of stem. Severity of disease is more if soil is infected with root knot nematode. Higher dose of nitrogen increases the disease intensity and higher dose of potash reduces it. Determined pathogen for wilt in muskmelon is Fusarium oxysporum f. sp. moniliforme, whereas, Sen and Palodhi (1979) observed dominance of Fusarium solani over Fusarium oxysporum.
i. Disease can be minimized by soil application of Trichoderma at the rate of 5-8 kg/ha.
ii. Treat the seed before sowing with carbendazim by dipping in 0.25% solution.
5. Anthracnose (Colletotrichum Orbiculare):
It is not a common disease of muskmelon but appeared sometimes and significant losses are occurred due to its attack. Disease symptoms are found on all above ground plant parts starting from cotyledonary leaf to true leaves, stem, and tendril. Light brown circular spots appear on the leaf, which later turns to deep brown.
Elongated lesions on stem and circular to oval sunken lesions appear on fruit, and subsequently, fruits shrivel, darken, and finally, dry up. Later on, the infected fruit rot and infect all the seed, which is source of further primary infection. It is seed born disease and seeds from infected fruits carry the primary inoculums for further infection.
i. Long crop rotation should be followed.
ii. Seed should be collected from disease-free plants.
iii. Seeds can be treated with carbendazim (2.5 g/kg of seed) before sowing.
iv. Foliar spray of systemic fungicide such as carbendazim 0.1% has been found effective to control the disease.
v. Spray of chlorothalonil 0.2% also gives good control of this disease.
vi. The disease debris should be burnt.
6. Cucumber Green Mottle Mosaic Virus (CGMMV):
Major symptoms of CGMMV are slight clearing of veins and crumpling of the young leaves followed by a light or dark green mottle together with blistering and distortion of leaves. The CGMMV was first time reported from India in bottle gourd. This virus is naturally infected the muskmelon. The cucurbit beetle is able to transmit the virus to the extent of 27%, however, it is never transmitted through seed.
They had also reported that contaminated irrigation water also plays important role in spreading this disease. The virus is very stable and mechanically transmissible at the time of cultural operation or pruning or simple by rubbing of infected leaves.
i. Early sowing of crops may reduce the disease due to low vector population.
ii. Avoid contamination by workers and implements.
iii. Spray Dimethoate or metasystocs (1 ml/l) at 10 days interval to manage the vectors.