Reports of damage by grasshopper Zonocerus variegatus (L.) to cassava and other crops has increased in recent years. The attack on cassava is particularly threatening to the livelihood of many poor subsistence farmers in Sierra Leone. As such, an evaluation was conducted to investigate the use of host plant resistance as an alternative method of managing grasshopper rather than the sole reliance on chemicals. The experiment was laid out in a randomized co mplete block design with three rep lications. Two b locks were used (protected and unprotected) with twenty cassava varieties (Slicass 1 05-21, VT 05-02, Slicass 2, SN 05-22, Slicass 1 05-14, Slicass 2 05-17, Slicass 5, VT 05-07, SN 05-41, Slicass 1 05-05, 97/ 3202-05-04, Slicass 4, Slicass 1 05-42, SN 05-17, Slicass 1, Local, 97/ 0057-05-04, Slicass 6, 97/0057-05-01 and Slicass 2 05-13) in each block. Pest assessments was done at 3, 6, 9 and 12 Months After Planting (MAP) which co incides with the various seasons; rain, dry and dry-rainy transition periods. Significant differences were recorded in percentage incidence and severity score with respect to cassava variety and time of observation. While seven cassava varieties (Slicass 5, VT05-02, Slicass 4, 97/0057-05-04, 97/0057-05-01, slicass 6 and Slicass 1 05-21) were found to be less susceptible to Z. variegatus (L.), four varieties (Slicass 2 05-17, Slicass1 05-41, Slicass 2 05-13 and 97/005-05-04) out yielded (in terms of tuber weight and nu mber) the released varieties during the two cropping seasons. Percent incidence and severity score was relatively high at 6MAP and 9MAP. Overall, tuber weight and number were higher in the protected plot compared to the unprotected plot during the two cropping seasons. Hence, protecting cassava field fro m grasshopper infestation may increase yield, number o f tubers and invariably the production of good quality planting material that is resistance to grasshopper attack.

Notwithstanding the importance of tomato in human diet, the average yield of the crop in Africa hardily exceeds 7.5 tha -1 . There is continuous unavailability of high yielding cultivars that are adapted to diverse environment and suitable for different purposes. Consequently, evaluation of introduced tomato genotypes for desired horticultural characteristics to identify superior genotypes for additional improvement in yield and yield related traits is indispensible. Hence eight tomato (Solanum lycopersicum L.) genotypes including parental were field planted in a randomized complete block design with three replications at the Department of Horticulture Nursery Unit, School of Natural resources Management, Njala University, Njala Campus, Moyamba District, Southern Sierra Leone to evaluate them for good horticultural traits. Data collected include plant height at 50% and 100% flowering, stem girth at 50% and 100% flowering, days to first, 50% and 100% flowering, days to maturity, number of fruits set per plant, number of fruits harvested per plant, average fruit weights, fruit length, fruit diameter, fruit flesh thickness, locule number, marketable and nonmarketable fruits per plant. Results from the study indicated that all genotypes studied are adaptable to the Sierra Leone climatic conditions. P 1 (097) recorded the highest number of fruits set per plant, number of fruits harvested per plant and tallest and largest plant height and stem girth at 100% flowering. BC 2 F 2 had the highest locule number while R 3 P 9 had the heaviest fruit weight. P 2 (213) had the thickest fruit flesh thickness and longest duration to fruit maturity respectively while P 1 (097), BC 1 F 2 and R 3 P 9 had the same number of shortest days to maturity. Regarding fruit length and diameter, R 3 P 8 and R 6 P 6 had the longest and widest. With respects to marketable and nonmarketable fruit per plant, P 1 (097) recorded the highest correspondingly.

This study was aimed to assess weed species diversity and composition in cassava monoculture at Crop and Soil Sciences Department research field, Kwame Nkrumah University of Science and Technology, Kumasi. The experimental design was a randomised complete block design and replicated four times. The treatment factors were six weeding methods (Butachlor (4L/ha) + 2 hoe-weedings, Terbulor (4L/ha) + 2 hoe-weedings, three hoe weedings, three cutlass weedings, weed-free and weedy check) and two cassava varieties (Ampong and Dokuduade). Twenty-five weed species belonging to twelve different families were recorded and overall weed flora was composed of 80% broad-leaved weeds, 12% kinds of grass and 8% sedges. The results revealed that Cyperus rotundus, Spigelia anthelma and Panicum maximum were the three dominant and major weed species. Panicum maximum recorded the highest relative frequency while Spigelia anthelma and Cyperus rotundus showed higher values of relative density, relative abundance and important value index under both varieties.

A study on rapid propagation of cassava through tissue culture was conducted with three elite cassava genotypes: Slicass 6, Slicass 11 and Cocoa from Sierra-Leone. They showed slow growth in Murashige & Skoog (MS) basal medium which was proven to be optimal for a vast number of cassava accessions. Prior to mutation induction, a large population needs to be produced for mutagen susceptibility test and for mutant population development. The ultimate objective of this study was to investigate the effects of plant growth regulators on the shoot development of three cassava genotypes. In vivo shoot tips were sterilized and sub-cultured on MS media supplemented with six combinations of plant growth regulators (PGRs) at different concentrations. The results showed that from all media used, the MS medium with 1.0 mg/L α-naphthalene acetic acid (NAA) showed the best response for rooting (5.50), fresh weight (0.29 g), root number (10.00) and plantlet height (3.81 cm), while 0.1 mg/L 6-benzylaminopurine (BAP) was found to be more favourable to shoot development of leaves (6.38). The highest plant height and fresh weight were 3.81 cm and 0.29 g, respectively for Cocoa at 1.0 mg/L α-naphthalene acetic acid (NAA), 10.00 roots for Slicass 6 at 1.0 mg/L, 6.37 leaf numbers for Slicass 11 at 0.1 mg/L 6-benzylaminopurine (BAP) and 5.6 at 1.0 and 1.5 mg/L α-naphthalene acetic acid (NAA). These observations indicate that a supplement of 0.1 mg/L 6-benzylaminopurine (BAP) in MS medium can be useful in propagation of recalcitrant cassava and low concentration of α-naphthalene acetic acid (NAA) will be beneficial in root induction prior to acclimatization with promotion in recovery of the ex vitro plants before field assessment.

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Field trials were conducted in savannah woodland (Njala) and rainforest (Serabu) agroclimatic regions of Sierra Leone during 2016 second cropping season to assess different preemergence herbicides techniques that is efficient, cost effective and environmentally safe in cowpea production. The experiment consisted of 20 treatments which included 2 cowpea genotypes (slipea 4 and slipea 5) and 10 different weed control techniques viz: butachlor 50% emulsifiable concentrate (EC), double force®, power force® applied as preemergence herbicides at 2, 4 and 6 L ha-1, respectively and weedy check. The treatments were laid out in a strip-plot design arranged in a factorial system with three replications. The results of this study revealed that the application of power force® at 6 L ha-1 recorded the highest phytotoxic effect, lowest weed dry weight, number of pods per plant and grain yield, highest total variable cost, lowest gross and net returns. Furthermore, butachlor 50% EC at 2 L ha-1 closely followed by double force® at 6 L ha-1 resulted in maximum grain yield, gross and net returns compared to the rest of the other weed control techniques. Thus, it is concluded that butachlor 50% EC at 2 L ha-1 was more economical, profitable and beneficial than other control treatments in the production of cowpea genotypes in the savannah woodland and rainforest agroclimatic regions of Sierra Leone. Conclusively, the relationship between phytotoxicity and grain yield indicates that the higher the grain yield the lower the phytotoxic effects of the chemicals.

Okra is a very important vegetable in the field of nutrition and health care in Sierra Leone. The major limiting factors in okra production are incidence of insect pests and improper plant spacing. The present field research was undertaken at the Department of Crop Protection, School of Agriculture, Njala University to evaluate the effect of plant spacing on insect pest population, growth and yield, and profitability of okra production in Sierra Leone from 2017 to 2018 main cropping seasons. Five levels of plant spacing 50 cm × 40 cm (50,000 plants per hectare), 60 cm × 30 cm (55,556 plants per hectare), 60 cm × 40 cm (41,667 plants per hectare), 70 cm × 30 cm (47,619 plants per hectare), and 70 cm × 40 cm (35,714 plants per hectare) were adopted as treatments with three replications in randomized complete block design. The results of analysis of variance revealed that plant spacing were significant (P < 0.05) on insect population, plant height, leaf area, damage leaves, yield and yield components of okra at 4 and 8 weeks after planting (WAP) during 2017 and 2018 main cropping seasons. Okra cropped in plant spacing 50 cm x 40 cm (Recommended rate) inclined the highest number of insects, plant height, leaf area, damage leaves and yield at 4 and 8 WAP in both years followed by 60 cm x 40 cm plant spacing, while the reverse also holds true with 70 cm x 40 cm plant spacing. The profitability analysis revealed that the recommended plant spacing of okra (50 cm x 40 cm) produced the highest gross margins of Le 18,333,000.00 plants per hectare (ha-1) and Le 21,363,000 plants per hectare (ha-1) respectively during 2017 and 2018 main cropping seasons of okra production. In conclusion, increasing the plant spacing above the recommended plant spacing (50 cm x 40cm) could reduce insect population and leaf damage on okra, but will significantly decrease okra growth and yield, and profitability. Hence, in order to achieve maximum productivity of okra in the Njala area, the Clemson spineless variety of okra should be planted at a plant spacing of 50 cm x 40 cm. However, integrating plant spacing with other cultural methods of controlling insect pests of okra should be investigated in order to determine a sustainable and cost-effective method of controlling insect pests of okra.

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