Leek and shallot 385
January to March, and September to December (Currah and Proctor, 1990). A few
plantings are made in August, although the bulk of the crop is planted during October
with little planting until January (Jenkins, 1954). Sinnadurai (1973) described the
growing system for shallots in the coastal area of Ghana. The shallots are planted on
raised beds in sandy soils 7 cm apart. About four tons of bulbils are required for
planting one hectare. In Indonesia, 900–1000 kg of planting material is needed for
one hectare. Plants are spaced 15 ¥ 15 cm to 20 ¥ 20 cm according to the cultivar. At
planting, the tops are cut if the bulbs are dormant (Currah and Proctor, 1990).
A plant will produce from two to fifteen bulblets per cluster. The crop is propagated
by dividing the bulb clusters and planting individual bulblets, or cloves, 5 cm deep,
10 cm apart, in rows 30–60 cm apart. Warm temperatures and long photoperiods
favour bulbing.
22.8.6 Manuring and fertilization
The shallot crop is given a basal dressing of fertilizers or mixed fertilizers 10–15
days after planting and is then fertilized at two-week intervals until two weeks before
harvest with 200 kg of urea per hectare on each occasion. Muhadjir and Kusumo
(1986) planted cultivars Ampenan and Medan with a basal dressing consisting of 100
kg each of N and P 2 O 5 and 0, 50, and 100 kg of K 2 O per hectare. The highest yields
were obtained with 100 kg each of N and P 2 O 5 , and 50 kg K 2 O. The quantity of
nitrogen used had no influence on growth, leaf colour, susceptibility to bolting, or
number of bulbs, however, increasing nitrogen had an adverse effect on the uniformity
of leaf canopy at maturity, and 60 kg of nitrogen is recommended.
22.8.7 Culture
Shallots should be grown in the same way as onions. Plants that are not heavily cut
will proceed to form many bulbs attached together forming a clump. Shallot bulbs
often develop on top of the ground. Do not cover them with soil (Lane Greer and
George Kuepper, 1999).
22.8.8 Diseases and insect pests
The main diseases and pests are: anthracnose (Colletotrichum gloeosporoides), basal
rot (Fusarium oxysporum), downy mildew (Peronospora destructor), moulds
(Aspergillus niger, Penicillium corymbiferum, Penicillium cyclopium), neck rot (Botrytis
allii), onion blast (Botrytis squamosa), pink root (Pyrenochaeta terrestris), purple
blotch (Alternaria porri), smudge (Colletotrichum circinans), white rot (Sclerotium
cepivorum, Sclerotium rolfsii), nematodes (Ditylenchus dipsaci), thrips (Thrips tabaci),
beet armyworm (Spodoptera exigua) and other Spodoptera sp. caterpillars, as well as
a number of virus diseases (Currah and Proctor, 1990; Grubben, 1994; Kuruppu,
1999).
Loss of shallot yield from pests and diseases is common all over the world, and
chemical treatment is the major means currently used to reduce damage (Anon.,
1986; Suhardi, 1996). However, good agricultural practices can be used to partially
control losses. Practices that are essential for high-quality long-keeping yields include
crop rotation, drip irrigation (which is preferred over sprinkler irrigation to maintain
low air humidity), proper spacing to allow free passage of air so as to reduce the