Slow decline is an weakening disease of pepper. The disease is caused by both fungus and nematode. The affected vine dies after a period of 2-5 years. Therefore, managing the disease at the right time is very much important.
The diseases are characterized by aerial symptoms of foliar yellowing, defoliation and die-back.
The affected vines exhibit varying degrees of root degeneration due to infestation by plant parasitic nematodes.In severe cases withering and defoliation are noticed.
Foliar yellowing starts after the north-east monsoon from October-November and reaches its maximum during April-May coinciding with the summer
Onset of south west monsoon during May/June, some of the already affected vines recover and put forth fresh foliage. However, the symptoms reappear in subsequent seasons after the cessation of the monsoon and the diseased vines gradually loose their vigour and productivity.
The affected vines show varying degrees of feeder root loss due to infestation by plant parasitic nematode Radophalous similis and the expression of symptoms on the aerial parts occur after a considerable portion of the feeder roots are lost.
Root galls are noticed if plants are infested by root knot nematode Meloidogyne incognita.
Such damage to root tissues leads to rotting of feeder roots. This can be caused by nematodes and Phytophthora capcisi either independently or together in combination.
Survival and spread
- Fungus survives in disease plant debris.
- Cysts and egg masses in infected plant debris and soil or collateral and other hosts like Solonaceous, Malvaceous and Leguminaceous plants act as sources of inoculums.
- Rainy seasons and loamy light soils favours the development of disease
Management of the disease
- Severely affected plants with less than 50% of the canopy may be removed along with root system and burnt off. Treat the pit with copper oxychloride 0.2%. Replanting to be taken up during the next year with healthy planting material.
- In areas severely infested with root knot nematodes, planting of the resistant variety ‘Pournami’ is recommended. Biocontrol agents like Pochonia chlamydosporia and Trichoderma harzianum can be applied @ 50g/vine twice a year (during April- May and September-October).
1. Good Agricultural Practices (GAP) – Black Pepper by Directorate of Arecanut and Spices Development,Calicut, Kerala, India