Spices and Condiments

Pests and diseases

Pests

• Although 21 insect species are associated with the crop, only a few of them cause severe damage.
Leaf-eating caterpillars (Clelea plumbioda)

• The caterpillars feed gregariously on the chlorophyll of the leaves, leaving only the veins and midribs.
  
• Eupterote fabia is a sporadic polyphagous pest, causing severe damage to the crop.
  
• The larvae feed voraciously on the leaves causing complete defoliation and reduction in yield.
  
• Spraying of Fenitrothion 50 EC (0.05%), Dichlorvos 40 EC (0.03%) and Carbaryl (Sevin 50 WP 0.02%) is effective in controlling the leaf-eating caterpillars.
Borers (Glypheptenix sp.)

• This pest is specific to large cardamom.
  
• The young larvae bore into the shoot and feed on the central leaf core causing 'dead heart' symptoms, finally resulting in the death of the shoot.
Scolytid beetle

• Scolytid beetles are serious pests of immature capsules.
  
• They feed on the soft seed mass and make the capsule hollow.
  
• Spraying of Thiodan (0.1%), Nuvacron (0.1%), Ekalux (0.1%) and Dimecron (0.1%) controls the pests.
Leaf-eating beetles and weevils

• Chrysamela chlorine and Basiolepta femoratums scrape away the green matter of the leaves resulting in the formation of numerous perforations on the leaf surfaces.
  
• The application of Thiodan (0.1%) and Nuvacron (0.1%) controls the pest.
Aphids

• Most of the aphids are associated with the transmission of virus diseases, hence the damage caused by them is mostly indirect.
  
• However, a few of them cause different adverse effects by colonising at the base of clumps.
  
• Among the aphids, the banana aphid (Pentalonia nigronervosa), the cardamom aphid (P.caladi), pink aphid (Micromyzus kalimpongensis) and corn aphids (Ropholosiphum maidis and R.padi) are important.
  
• They can be controlled by spraying Rogor or Dimecron (0.1%).
Root grubs

• Polyphagous white grubs, which are c-shaped, infest the roots and rhizomes.
  
• Dusting Heptachlor (5%) and Aldrin dust (5%) controls the grubs.
  
• The leaf hoppers, Kolla mimica and K.opponens; the thrips, Rhipiphorothirps cruentatus; and mealy bugs are considered as minor pests.
  
• Cardamom moth and psocids damage the cardamom in storage.

Nematodes

• Root-knot nematodes, such as, Meloidogyne sp. infest large cardamom.
  
• The affected seedlings are stunted with numerous thin grassy shoots.
  
• Drenching the nursery beds with Formaldehyde (2%) and covering them with polythene sheets for 72 hours and treating the beds with granular nematicides like Carbofuran or Aldicarb was found effective in controlling nematode infestations.
Other pests

• Rodents, monkeys and wild cats are also serious pests attacking plantations during the harvest period and it is suggested that poison baits and traps are the best methods to control these pests.

Diseases
Viral disease

Chirkey

• This is a major disease of large cardamom.
  
• The corn aphi Rhopalosiphum maidis, R. padi and Brachycaudus helichrist are the vectors for the disease.
  
• The symptoms of the disease are very similar to that of Watte' disease in small cardamom.
  
• In the young leaves, discrete pale green or yellow longitudinal stripes running parallel to each other can be seen, but in the mature leaves these symptoms are masked.
  
• In the advanced stages, flecks measuring about 2.5 mm and the characteristic mosaic symptoms are also seen.
  
• The affected plants produce flowers and spikes but without capsules.

Forkey

• The Forkey disease causes severe damage in the Darjeeling district of West Bengal.
• It is transmitted through the vector Micromyzus kalimpongensis.
• This disease is characterised by production of bushy growth of stunted shoots which are sterile.
• Diseased plants survive for a few years but remain sterile and unproductive.
Control

• The infected plants should be uprooted and the surrounding area drenched with systemic insecticides (Rogor or Dimecron or Metasystotox at 0.1%) to check the aphid population as well as the movements on the main host and collateral hosts such as corn, banana, peach and squash,
• Collateral host plants in the vicinity should be destroyed.
• Planting rhizomes/slips collected from diseased plantation should be avoided.
  
• Healthy seedlings raised from good seeds should be used.

Fungal diseases

Seedling-rot and collar-rot

• Collar-rot, caused by Fusarium oxysporum, is very destructive to large cardamom plantations.
  
• At the nursery stage, it is called seedling-rot and at maturity stage, it is called collar-rot, clump-rot or spike-rot.
  
• The primary symptoms include paleness of the leaves followed by yellowing and decaying of the collar, which gradually extends towards the base.
  
• Normally, the flowers also remain unopened, and even if a few do open, they do not bear fruits and ultimately the spikes rot or wilt.
  
• This disease is locally called `agulata'. Continuous rainfall during the flowering period, water stagnation and old plantations with degenerated clumps favour the spread of this disease.
Leaf-spot

• This is also widespread in occurrence and is caused by two pathogens, viz., Pestalotiopsis vesicolor and P. royenae.
  
• The former produces angular, irregular spots with reddish-brown margins surrounded by chlorotic holes and is characterised by numerous, elongated, transluscent streaks appearing on the young leaves along the veins. The streaks turn reddish-brown within 3 to 4 days with a central straw coloured necrotic area surrounded by prominent dark brown margins.
Leaf rust

• The rust disease, caused by Phakospora eleuaria, is observed on the ventral surface of the lower leaves in the form of numerous minute, brown uredosori mainly in May and June. In the early stages of development, the uredosori are surrounded by chlorotic holes.
  
• In the advanced stage, the whole leaf is covered by uredosori causing premature drying of the leaves.
Capsule-rot

• This is caused by Pestalotiopsis sp. The affected capsules become slimy, water-soaked and have a discoloured appearance. The seeds from diseased capsule emit a foul smell.

Control of fungal diseases
• Cultural practices, such as rouging of plants, field sanitation by providing drainage in nurseries and plantations, removal of diseased debris and weeds are effective in controlling the diseases.
  
• Drenching/ spraying once or twice before the onset of the monsoon and just after flowering with Bavistin (0.3%), Rovral (0.5%), Captafol (0.2%), Bordeaux mixture (1.0%) or Dithane M-45 (0.25%); and drenching the soil with Thiram (0.2%) or Dithane M-45 (0.25%) during February- March in and around the clumps are a few general control measures.