AN EVALUATION OF HERBICIDE TREATMENTS FOR THE CONTROL OF Aleclra Vogelii Benth and Striga gesnerioides (Wild) Vatke IN COWPEA (Vigna unguiculata (Li WALP)
AN EVALUATION OF HERBICIDE TREATMENTS FOR THE CONTROL OF Aleclra Vogelii Benth and Striga gesnerioides (Wild) Vatke IN COWPEA (Vigna unguiculata (Li WALP)
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Date
1999-04
Authors
CHIBIYA, PAUL SHINGGU
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Abstract
Seed treatment of acetolactate synthase (ALS) inhibitor herbicides, cinosulfuron
and CGA152005 were evaluated for the control of parasitic weeds, Alectra vogelii Benth
and Striga gesnerioides (Wild.) Vatke in cowpea (Vigna unguiculata (L.) Walp) at the
Institute for Agricultural Research, Ahmadu Bello University, Samaru during the 1994
dry and 1995 wet seasons. The treatments consisted of five cowpea varieties (IT81D-985,
SAMPEA 7, SAMPEA 6, IT90K-102-6 and IT89KD-245-1) and 10 herbicide seed
treatment, cinosulfuron at 0.05, 0.1, 0.2 and 0.4 and CGA152005 at 0.008, 0.016, 0.032
and 0.064 g/1 including the water soaking and dry planting no herbicide controls. The
treatments were laid out in in completely ramdomized design (CRD). In the laboratory
and screen house and split plot design in the field varieties were the main plot treatment
while the seed treatments were allocated to the sub-plots. The cowpea varieties IT90K-
102-6 and IT81D-985 were susceptible to the herbicide seed treatments evaluated as
reflected in depression in seed germination, poor stand establishment as well as high
injury and low crop vigour score with and without parasitic weed infestation in the screen
house. The nodulation of the cowpea varieties was also lower than the maximum
obtained with IT89KD-245-1 with and without parasitic weed infestation in the field.
Variety IT90K-102-6 also produced lower leaf dry matter than the maximum produced
by SAMPEA 6 in the trials. The variety SAMPEA 6 produced higher cowpea grain yield
than SAMPEA 7 and IT81D-985 inspite of high parasitic weed infestation and incidence.
Cowpea variety SAMPEA 7 produced the least 1000-grain weight with and without
parasitic infestation while IT89KD-245-1 produced the heaviest seeds. Both SAMPEA-7
and SAMPEA 6 supported the highest infestation and incidence of Striga and Alectra in
the study. IT89KD-245-1 and IT90K-102-6 however supported lower number of Alectra
and incidence than the varieties and IT81D-985. Striga emergence was also delayed on
varieties IT81D-985, IT89KD-245-1 and IT90K-102-6 compared with SAMPEA 6 and
SAMPEA-7.
The seed treatments differentially affected parasitic weed infestation and incidence as well
as the vigour, growth and yield of cowpea. CGA152005 at 0.064g/l with Alectra
infestation and at 0.032 and 0.064g/l with infestation caused significantly higher injury
score of cowpea compared with the lower concentrations and no-herbicide controls.
Similarly, the highest ratesr of the two herbicides CGA152005 at 0.064g/l and cinosulfuron
at 0.04g/l resulted in lower vigour score than their corresponding low concentrations in
the screen house with and without Alectra inoculation. CGA152005 at 0.032 and 0.064g/l
also reduced shoot dry weight of cowpea significantly compared with the no-herbicide
controls. Similarly the nodulation of cowpea was depressed by cinosulfuron at 0.2 and
0.4g/l and CGA152005 at 0.016 to 0.064g/l with parasitic weed infestation. Under
parasitic weed infestation, CGA 152005 at 0.032 and 0.064g/l however produced
significantly higher cowpea grain yield than cinosulfuron at 0.05 and 0.1g/l, CGA152005
at 0.008g/l and dry planting control as a result of effective reduction of parasitic weed
infestation. Cinosulfuroin at 0.04g/l and the planting of water-soaked seeds also resulted
in higher cowpea grain yield than dry planting no-herbicide control. Cinosulfuron at 0.2
and 0.4g/l and CGA152005 at 0.032 and 0.064g/l significantly delayed the emergence of
the parasitic weeds in the screen house and field. Alectra/Striga emergence was also
delayed by cinosulfuron at 0.4g/l and CGA152005 at 0.064g/l compared with the lower
rates while cinosulfuron at 0.2g/l and CGA152005 at 0.032g/l delayed Striga emergence
only. The herbicide seed treatments reduced the number of emerged and unemerged
Alectra in the screen house and Alectra/Striga shoot infestation and incidence on cowpea
in the field. CGA152005 at 0.032 and 0.064g/l caused more effective reduction of
infestation than the other herbicide treatments.
Yield loss due to the parasitic infestation was 12.7% for SAMPEA 6 to 34.7% for
SAMPEA 7. The interactions of varieties and herbicide seed treatments on number of
days to 50% flowering without parasitic weed infestation was significant in the trial
Description
A thesis submitted to the Postgraduate School,
Ahmadu Bello University, In Partial Fulfillment
of the Requirements for the Degree of Master
of Science in Agronomy
Department of Agronomy
Faculty of Agriculture
Ahmadu Bello University
Zaria, Nigeria
April, 1999
Keywords
EVALUATION,, HERBICIDE,, TREATMENTS,, CONTROL,, Aleclra Vogelii Benth,, Striga gesnerioides (Wild) Vatke, COWPEA,, (Vigna unguiculata (Li WALP).