The main oilseed crops of Pakistan are rape and mustard, tory jambho, sesamum, castor and linseed. These oilseed crops have been grown traditionally and are known as conventional oilseed crops.

Due to rapid population growth, demand of edible oil has been steadily increasing at the rate of about 10 per cent annually, and the domestic production of edible oils (including cotton seed) hardly meet 25 per cent of the country’s requirement. To narrow the gap between the production and the consumption, introduction of some non-traditional oilseed crops were introduced from time to time.

During the green revolution in 1960s sunflower, soybean and safflower, and in 1990s canola (Brassica rumpus) were introduced in various parts of the country. But unfortunately despite efforts, the oilseed situation in Pakistan is not improving yet. The import bill for edible oil, which was Rs2.3 billion in 1979-80, has gone to Rs40 billion in 1988-1999.

Over the years the government launched various promotional programmes for oilseed crops, especially for non-traditional ones. At present the government is trying to grow palm oil trees in the coastal belt of Sindh and Balochistan. It is now, however, recognized that sunflower is the crop which has the potential to become a major oilseed crop, being a nice fit in some existing cropping pattern (rice-sunflower-rice-wheat) and adapted well to major agro-ecological condition of the country. Because of deep root system it needs less irrigation water as compared to other crops. In Sindh over 61 per cent of its acreage is confined to rice tract of south Sindh (Thatta and Badin district and Tando Mohammad Khan taluka of District Hyderabad) where sunflower is being raised on residual soil moisture in rotation with rice as a dobari crop.

However, in rice growing districts of upper Sindh it failed to give cost-effective yield because of variety of factors. In cotton growing districts of upper Sindh too, farmers are facing problem in adjusting the sunflower cultivation. The sowing time of sunflower and wheat is almost the same. Farmers have to make a choice between the competing crops. Since sunflower crop is subject to bird tenting and many insect pest and disease factors, farmers prefer wheat over sunflower. In nutshell it can be said that south Sindh is the only safe home for the sunflower oilseed crop in the province. But unfortunately in this very safe home too, sunflower remained no more safe now because of introduction of a new menace to this crop.

According to Pakistan Oilseed Development Board, this year sunflower sowing has greatly been affected by the massive population outbreak of field rats. Damage was seen just after sowing of sunflower seed. Modus operandi of rat damage was digging of seed and split open with the kernel consumed leaving the hull left on the soil. Extent of seed damage could be gauged from the fact that on hundred of acres farmers had to undertake resowing with costly seeds. However, the survey has indicated that rat outbreak area was restricted only to those cultivations undertaken as dobari crop in the rice field after paddy harvest.

According to rodent experts, Amjad Pervez and S. Mower Ahmed of Vertebrate Pest Control PARC, Karachi University Campus, their survey has indicated that Golarchi taluka in district Badin was the worst affected area by the rodent. The result of 150 trap nights revealed rice field rat was the main species of rats — 65 per cent, followed short tailed mole rat 20 per cent, and rest by soft-furred field rats, field mouse, and field shrew. Presence of paddy husk in the thrashing yards, stacking of harvested paddy adjoining sunflower fields, sugarcane cultivation in the vicinity, prevailing drought condition and extensive growth of weeds on bunds have been attributed to the present rat outbreak in district Badin. No doubt reasons of rat outbreak may be attributed to the aforementioned factors as observed by rodent experts.

But these factors as a matter of fact are not new ones, rather existing since so many decades and there was no report of rat damage to sunflower crop like the present development in that region. It is, therefore, warranted that some other factors which force rat population to feed upon seeds of sunflower after sowing in the paddy field as dobari crop may also be taken into account. According to a progressive grower of taluka Golarchi of district Badin, fast drying Indus delta is the main reason of present rat-outbreak in the district. The non-release of water in the river downstream Kotri for about five years has led to sea intrusion. So far, as some 1.2 million acres of agricultural land have been destroyed in Thatta and Badin districts due to submergence under sea water. Accordingly, non-availability of food (agricultural and weeds) over large areas might have forced migration of rat population to the area presently under rat outbreak.

Suggestions: Since extensive rat damage to the paddy crop in lower Sindh had seriously hampered development of this region in the past (1927), it is imperative that rat damage to sunflower crop, raised on residual soil moisture after paddy harvests, is seriously taken into account by the ministry of agriculture, both at the provincial and the federal levels.

Besides, to combat the rat menace, integrated pest management (IPM) is needed. The tool of IPM includes inspection, cultural control (prevention and habitat management) physical control (trapping and exclusion); biological control (predators — owls, raptors) and if needed chemical control (rodenticides and repellents). Unintelligent use of poison may result in the destruction of the big-diversity of the agro-ecosystem and weakening of the natural forces restraining pest population.