PLANTING TIME, SPRAY REGIME, DISEASE EXPRESSION AND THEIR IMPACTS ON SIX CUCUMBER LINES IN A DERIVED SAVANNA AGROECOLOGY OF NSUKKA, SOUTHEASTERN NIGERIA.
ABSTRACT
Cucumber (Cucumis sativus L.) belongs to the Cucurbitaceae family. It is a major vegetable crop worldwide and develops rapidly, with a shorter time from planting to harvest than most crops. It is a monoecious annual climber or creeper that has been cultivated for over 3,000 years and is still widely cultivated today. The fruit is soft, succulent with high water content, roughly cylindrical and elongated with tapered ends. The plant shades one another, being allowed to creep on the ground thereby having a direct contact with some soil inhabiting disease causing organisms. Its creeping nature, pre-disposes the plant to pest and disease infestation. However, the production of cucumber fruits in Nigeria is very low due to some constraints such as incidence of diseases which reduces fruit yield. Presently, they are produced mainly in the northern states of Nigeria. Studies were conducted on the production of cucumber in south eastern Nigeria, in order to supplement the high consumption rate in the region. Planting in April had the lowest disease incidence (3.48%) and severity on leaves (1.20) and fruits (1.06), followed by September with lower disease incidence (3.60%), disease severity on leaves (1.22) and fruits (1.17) while July had the highest disease incidence (6.27%) and disease severity on leaves(1.56) and fruits (1.74). The yields during the April and September plantings were significantly (p<0.05) higher than other months. April and September had 481.60 and 483.60 tonnes per hectare respectively while July had 19.10 tonnes per hectare. The spray regimes were significant (p<0.05) on the disease incidence and severity. The plants that received two weekly spray regime had the lowest disease incidence and severity on leaves and fruits (4.10%, 1.31 and 1.21 respectively) followed by those that recerived three and four weekly spray regimes. Those that were not sprayed had the highest disease incidence and severity on leaves and fruits. The plants that were sprayed fortnightly gave the highest yield of 216.90 tonnes per hectare. The cucumber lines also showed significant (p<0.05) response to disease incidence and severity with the Supermarketer having the lowest disease incidence (4.15%) and severity on leaves (1.39) and fruits (1.17) and Poinsette Holland had the highest disease incidence (5.15%) and Poinsette 76 Holland had the highest severity both on leaves and fruits (1.45 and 1.35). The supermarketer gave the highest yield of 221.10 tonnes per hectare. The best planting time remains April and September receiving fungicide spray fortnightly. Super marketer have also proven to be the best variety to withstand diseases and the weather condition of a derived savannah agro ecology.