Diseases of Ginger
Bacterial wilt or Prem Rog : Ralstonia solanacearum
Symptoms : It is the most serious disease and the symptoms can be noticed form July-August. The leaf margins of the affected plant turn bronze and curl backward. The whole plants wilt and die. The base of the infected pseudostem and the rhizome emit foul smell. When the suspected pseudostem is cut and immersed in a glass of clean water, milky exudates will ooze out from the cut end. Typical symptom is the wilting observed during afternoon in young seedlings.
Management : Seed contamination is the major source of infection. Hence, procure only healthy rhizome from disease free area. Treat the seed with Streptocyclin (20g/100 litre water). Remove the affected clumps and drench the soil with copper oxychloride 0.2%.
Soft rot or Paheli : Pythium aphanidrematum
Symptoms : It is a serious seed as well as soil borne disease and the symptoms can be seen from July. Yellowing of leaves appear first on the lower leaves and proceeds to upper leaves. Roots arising form the affected rhizome become rotten and show brown discoloration of the rhizome tissue. Sometimes the pseudostem comes off easily with a gentle pull. The rotten parts attract other fungi, bacteria and insects particularly the rhizome fly. During the rainy season, this disease spreads very fast from infected field to healthy field.
Management : Avoid water logging. At the time of sowing, treat the rhizome with Bordeaux mixture (1%) and again with Trichoderma @8-10-gm/litre water.
Remove the badly affected plants and drench around the infected plants, after slightly removing of soil with Bordeaux mixture (1%) or copper oxychloride @ 2g/1 liters of water.
Dry rot : Fusarium and Pratylenchus complex
Symptoms : It is a fungus-nematode complex disease. In contrast to rhizome rot, dry rot appears in field in small patches and spreads slowly. The affected plants appear stunted and exhibit varying degree of foliar yellowing. Older leaves dry up first followed by younger ones. In advanced stage the rhizome, when cut open, show a brownish ring and is mainly restricted to cortical region. The pseudo stem of the dry rot affected plants does not come off with a gentle pull in contrast to soft rot. The affected rhizomes are shrunken, dry and are not marketable.
Management : Soil application of mustard oil cake at the rate of 40 kg/ha before sowing in furrows can check the nematode problem. Hot water treatment (51OC for 10 min) followed by seed treatment with Bordeaux mixture (1%) effectively checks the problem.
Leaf spot / blight : Phyllostricta zingiberi
Symptoms : Small spindle to oval spots appear on younger leaves. The spots have white papery centers and dark brown margins surrounded by yellowish halos. The spot later increase in size and coalesce to form larger spots which eventually decrease the photosynthetic area. In the case of severe infection the entire leaves dry up.
Management : Spray Bordeaux mixture (1%) 3-4 times at 15 days interval with the initiation of the disease. Good control is achieved by growing the crop under partial shade.
Insect Pests of Ginger
White Grub or Khumlay : Holotrichia spp.
It is a sporadic pest, sometimes causes serious damage. The grub feeds on the roots and newly formed rhizomes. The infestation is generally more during August-September. The adult beetles, after emergence from pupae settle on the Ficus or other trees in congregation which can be collected and destroyed. The entomophagous fungus Metarrhizium anisophilae can be mixed with fine cow dung and then applied in the field to control the grubs. In endemic areas opt for soil application of neem cake @ 40 kg/ha before sowing.
Shoot borer :Conogethes punctiferalis
The larvae bore the tender pseudostem and reach the central portion by feeding on the internal tissues, thus resulting in yellowing and drying of shoots. Infestation may occur from June to October. Spray Nimbicidine (2-5ml/l) or Beauveria bassiana@ 2-5ml/l
Shoot boring weevil : Prodioctes haematicus
The grubs bore into the pseudostem and cause dead hearts. Remove alternate host plants such as wild turmeric and cardamom. The congregating adult beetles can be collected and destroyed. Spray Nimbicidine @ 2-5ml/l or Carbofuran 3G granules @ 30 kg/ha immediately after mother rhizome extraction. In the case of severe infestation, spray Endosulfan @ 0.07 %.
Integrated Pest and Disease Management for Ginger
- 1. Field hygiene is more important to manage the pests and diseases. Avoid water stagnation, provide adequate drainage, remove weeds periodically, apply only well rotted FYM compost @ 25 t/ha and thoroughly incorporate it in the soil, apply dolomite @ 2 t/ha before sowing to increase soil pH, sow ginger in raised beds of at least 25-30 cm height and provide mulching with leaves and twigs of chilaune (Schima wallichii) or Banmara (Eupatorium sp) or utis (Alnus nepalensis) or mustard oil cake @ 5 to 10 t/ha and follow crop rotation of 2 to 4 years depending on the incidence and severity of the diseases. Soil application of Biocontrol agents like T. harzianum and P. fluorescence during planting time @ 2-5% gives effective control of the diseases.
- 2. Use good quality rhizome for sowing. Procure disease free seeds from disease free area.
- 3. Before sowing, treat the rhizome in hot water (51oC for 10 min) and again in solution of Bordeaux mixture 1% for 15 min. Add Streptocyclin (20g/ 100 l water) if bacterial wilt is also a problem. Dry the rhizome in shade and then sow. If cut rhizome are to be planted, they should be treated after cutting.
- 4. Treat rhizome with bio-inoculant Pseudomonas fluorescens and Trichoderma harzianum followed by soil application 60 days after planting to reduce rhizome rot.
- 5. Once the diseases is spotted in the field, remove the affected clumps and drench the soil with Bordeaux mixture 1% at 15 days interval.
- 6. Diseased plants should be identified while the crop is in field. Rhizomes from such plants should not be selected for the seed purpose
- 7. Mechanical collection and destruction of grubs, weevils, larvae and adult beetle periodically will reduce the incidence of insect pests. If white grub is predominant, apply Nimbicidine @ 2-5 ml/ l.
- 8. It has been observed that diseases spread fast after mother rhizome (mau) extraction. Hence, drench the soil with fungicide immediately after mau extraction and again this practice has to be followed keeping into consideration the cost – benefit ratio of mau extraction and disease incidence.
Source: R. Karuppiyan, H. Rahman, R.K. Avasthe, H.Kalita, Matber Singh, K.Ramesh, P.K. Panda, Ashok Kumar and Tasvina Rahman Borah, ICAR Research complex for NEH Region, Sikkim center, Tadong, Gangtok – 737 102