TUYEÅN TAÄP

There are not enough resistant varieties to drought, flood and salty, etc. for each
suitable area. At present, most exotic varieties occupied high ratio of the acreage like F156,
My55-14, VN84-4137, VN84-422, VN85-1859, ROC1, ROC10, RO16, etc. Commercial
varieties haven’t shown good tonnage, viguor and quality characters. Shortage of varieties
have resistance to diseases (smut, with leaf, yellow leaf syndrome, etc.) and bores (Sesamia
sp., Phragmatoecia castaneae Hubner, Scirpophaga nivella Fabr.,Chilo sacchariphagus Bojer,
etc.). Meanwhile, the problems of bores are very importance; it is main reason for drop
sugarcane yields. Many regions are scattered with small areas under sugarcane production;
those are difficult to work by cultural machine. Especially, sloping hill (in the North and
Centre) and low land (Mekong delta). Many factories are getting shortage of raw material for
working at full capacity. The high land regions are depending on rainfall for growth sugarcane
and low land regions are usually flooded by water. In contrast, there are not many of good
irrigation or good hydraulic systems as necessaries. Especially in the Eastern South zone,
bores dropped yielding cane in many recent years. The competitive culture between sugarcane
and many valid crops are always violence.
The sugar cane bores in Vietnam
There are 8 species of sugarcane bores in Vietnam (Table 1.), the cane could be
damaged in all state of growing. The cane yield could be lost by them average of 20-40% per
year. Three of them were vary dangerous to cane from planting to harvesting as Phragmataecia
castaneae Hubner, Sesamia sp. and Chilo sacchariphagus Bojer, with frequency of them in the
field are 35.23; 33.54 and 22.44% to respond to each other.
Table 1. Major species of sugarcane bores in Vietnam
Name
Family
Phragmataecia castaneae Hubner
Cossidae
Sesamia sp.
Noctuidae
Sesamia inferens Walker
Noctuidae
Chilo sacchariphagus Bojer
Pyralidae
Eucosma schistaceana Snellen
Eucosmidae
Chilo auricilius Dudgeon
Pyralidae
Scirpophaga nivella Fabricius
Pyralidae
Chilo infuscatellus Snellen
Pyralidae
The ratio of damaged cane in the field caused by three bores were 35.38, 22.33 and
32.89% in order. The cause of them is not low yield cane and bad quality.
Table 2. Density of species and their damage on the cane field in
the Eastern South zone (8/1999 - 8/2001)
Species
Density of species
Damaged
cane by
bores
(%)
No. of larva
Ratio of species to total
(%)
Phragmataecia castaneae Hubner 1,615 35.23 35.38
Sesamia sp. 1,534 33.54 22.33
Chilo sacchariphagus Bojer 1,027 22.44 32.89
Sesamia inferens Walker 65 1.4 0.7
Eucosma schistaceana Snellen 149 3.26 5.04
Chilo auricilius Dudgeon 98 2.14 1.87
Scirpophaga nivella Fabricius 76 1.65 1.65
Chilo infuscatellus Snellen 16 0.34 0.14
Total 4,570 100.0 100.0
213