Two years of field studies were carried out to study the effect
of three planting dates of cowpea, April 1st, 15th and 30th, on the
levels of infestation by different pests, namely: Tetranychus
uit/cae, Tetranychus cucurbitacearum and whitefly, Bemi’/a tabaci
as well as Thrips tabad Also, the resultant yield was recorded.
Data revealed that the numbers of different stages of T uit/cae
were increased by delaying the planting date on cowpea plants.
Plant cultivated on April, Vt, 15th and 30th harbored 0.48, 1.40 and
2.15 eggs, 0.42, 0.72 and 1.31 mobiles, 0.90, 2.11 and 3.46 totals
/ leaflet, respectively.
The earliest planting date harbored the fewest mean number
of T cucurbitacearum, eggs, mobiles and total (0.40, 0.03 and
0.43/leaflet, respectively).
Lately sowing correlated with plants showed the lowest
infestation by different stages of white fly, B. tabaci [0.33
(eggs/leaflet), 0,12 (nymphs/leaflet) and 0.04 (pupae/leaflet), 0.03
(adult/plant) and 0.51 (individuals of total stages)].
The results included that the abundance of Thrips tabaci
individuals increased only in the early planting date, mean rates of
infestation in two seasons were (0.06, 0.05 and 0.02 nymphs, 0.01,
0.01 and 0.00 adult, 0.06, 0.05 and 0.02 individuals of total
stages/leaflet respectively).
Finally, the sowing in the earliest date (April, Vt) lead to have
the highest dry pods yield and the lowest infestation by the spider
mites, T uit/cae & T cucurbitacearum. |
