Abstract
Trials were conducted in Kano, northern Nigeria, during 1996 and 1997 cropping seasons to determine the influence of date of planting and two well-timed insecticides sprays on the incidence of major insect pests namely, the legume pod-borer, Maruca vitrata Fab., legume flower thrips, Megalurothrips sjostedti Trybom, complex of pod-sucking bugs and cowpea aphid, Aphis craccivora Koch and their effect on grain yield of elite cowpea (Vigna unguiculata L. Walp) cultivars from International Institute of Tropical Agriculture (IITA) breeding programme. Six cultivars were planted at 4 different dates between 13 June and 12 August 1996 whilst 12 cultivars were planted at 5 different dates between 5 June and 12 August 1997 with and without insecticide protection. Aphid infestation occurred only on cowpea planted between the first week of June and mid-July with the highest incidence recorded on crop planted in the last week of June. Cowpea planted in June flowered and podded between early to mid-August when post-flowering pests (M. vitrata, M. sjostedti and Clarigralla tomentosicollis) densities were relatively low and produced significantly higher grain yields without insecticide protection compared to other planting dates. The flowering and pod formation stages of late planted (July and August) crops coincided with the peak population densities of the three major post-flowering pests resulting in a considerable reduction of grain yield. Overall, IT90K-277-2, IT93K-734, IT93K-452-1 and IT93K-513-2 performed best whereas IT86D-719, IAR-48 and Dan Ila gave the poorest performance when unsprayed. Two insecticide sprays of Cypermethrin + dimethoate (Sherpa plus ®) (30 + 250g a.i. ha-1) at but initiation and 50% flowering stages increased grain yields considerably from 225 to 900 kg ha-1 for cowpea planted in July and August. Cost-benefit analysis indicated that the insecticide application was more profitable for cowpea planted in late July and August than was the case when planted in June and early July. This seems to suggest that early maturing elite cultivars could escape economic damage caused by post-flowering pests when cowpea is planted early in the season. The implication of these findings to the grower and the breeding strategy at IITA is discussed in this paper. RÉSUMÉ Des essais ont été conduits durant les saisons culturales de 1996 et 1997 à Kano au nord du Nigeria pour déterminer l'influence de la date de plantation et la pulverization de deux insecticides bien connus sur l'incidence des principaux insectes à savoir les boreurs des gousses des légumineuses, Muruca vitrata Fab., les thrips des fleurs des légumineuses, Megalurothrips sjostedti Trybom, le complexe des punaises pipeuses des gousses et les aphides du niébe, Aphis craccivora Koch et les effets sur le rendement grain des cultivars élites du niébe du programme d'amélioration de l'IITA. Six cultivars ont été plantés à quatre differentes dates entre le 13 Juin et le 12 Août 1996 alors que 12 cultivars ont été plantés à cinq differentes dates entre le 5 Juin et le 12 Août 1997 avec ou sans protection d'insecticide. L'infestation des aphides ont apparu seulement sur le niébe plantés entre la première semaine de juin et mi-juillet avec l'incidence la plus élevée observée sur les cultures plantées dans la dernière semaine de Juin. Le niébe planté en Juin a fleuri et formé des gousses entre très tôt et mi-Août quant les densités des pestes post floraison (M. vitrata, M. sjostedt et C. tomentosicollis) étaient relativement faibles et ont produit significativement des rendements grains très élevés sans insecticides comparés aux autres dates de plantation. Les stades de floraison et de formation des gousses des cultures plantées plus tard (Juillet et Août) ont coincidé avec les densités plus élevées de trois majeurs pestes pot-floraison résultant à une réduction considérable du rendement grain. En général, IT90K-277-2, IT93K-734, IT93K-452-1 et IT93K-518-2 ont été les meilleurs alors que IT86D-719, IAT-48 et Dan Iia ont eu une pauvre performance lorsqu'ils étaient no pulverisés. Les pulverizations de l'insecticide de Cypermethrin + dimethoate (Sheroa plus R ) (30 + 250g a.i ha-1) à l'initiation et 50% des stades de floraison ont augmenté les rendements grains considérablement de 225 à 900 kg ha-1 pour le niébe planté en Juillet et Août. L'analyse du coût-bénéfice a indiqué que l'application de l'insecticide était plus profitable pour le niébe planté tard en Juillet et Août plus que le cas du niébe planté en Juin et début Juillet. Ceci semble indique que les cultivars élites plus précoces pourraient échapper aux domages économiques causés par les pestes post floraison quant ils apparaissent avant dans la saison. Les implications de ces résultats pour les cultivateurs et la stratégie d'amélioration pour l'IITA sont dicutées. (Af Crop Science and Production: 2001 9(4): 655-666)
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Claims 10
Claim · model-written summary
Aphid infestation occurred only on cowpea planted between the first week of June and mid-July.
- Taxon
- cowpea
Vigna unguiculatat0 - Treatment
- planted between the first week of June and mid-Julye1
- Interactor
- Aphis craccivora
Aphis craccivorae0pest - Outcome
- Aphid infestatione1
- Direction
- occurred onlye1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e0“cowpea aphid, Aphis craccivora Koch”
e1“Aphid infestation occurred only on cowpea planted between the first week of June and mid-July with the highest incidence recorded on crop planted in the last week of June”
Claim · model-written summary
Aphid incidence on cowpea was highest on crop planted in the last week of June.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- crop planted in the last week of Junee1
- Interactor
- Aphis craccivoraAphis craccivorae0pest
- Outcome
- incidencee1
- Direction
- higheste1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e0“cowpea aphid, Aphis craccivora Koch”
e1“Aphid infestation occurred only on cowpea planted between the first week of June and mid-July with the highest incidence recorded on crop planted in the last week of June”
Claim · model-written summary
Cowpea planted in June produced significantly higher grain yields without insecticide protection than other planting dates.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- planted in Junee2
- Outcome
- grain yieldse2
- Direction
- highere2
- Qualifier
- without insecticide protectione2
- Comparator
- other planting datese2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e2“Cowpea planted in June flowered and podded between early to mid-August when post-flowering pests (M. vitrata, M. sjostedti and Clarigralla tomentosicollis) densities were relatively low and produced significantly higher grain yields without insecticide protection compared to other planting dates”
Claim · model-written summary
Post-flowering pest densities were relatively low on cowpea planted in June.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- planted in Junee2
- Interactor
- post-flowering pestse2pest
- Outcome
- densitiese2
- Direction
- relatively lowe2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e2“Cowpea planted in June flowered and podded between early to mid-August when post-flowering pests (M. vitrata, M. sjostedti and Clarigralla tomentosicollis) densities were relatively low and produced significantly higher grain yields without insecticide protection compared to other planting dates”
Claim · model-written summary
Late planted cowpea crops had a considerable reduction of grain yield where flowering coincided with peak post-flowering pest densities.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- late planted (July and August) cropse4
- Interactor
- post-flowering pestse4pest
- Outcome
- grain yielde4
- Direction
- reductione4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e4“The flowering and pod formation stages of late planted (July and August) crops coincided with the peak population densities of the three major post-flowering pests resulting in a considerable reduction of grain yield”
Claim · model-written summary
IT90K-277-2, IT93K-734, IT93K-452-1 and IT93K-513-2 performed best in unsprayed cowpea.
- Taxon
- cowpeaVigna unguiculatat0
- Material
- IT90K-277-2, IT93K-734, IT93K-452-1 and IT93K-513-2e5
- Outcome
- performed beste5
- Qualifier
- when unsprayede5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e5“IT90K-277-2, IT93K-734, IT93K-452-1 and IT93K-513-2 performed best whereas IT86D-719, IAR-48 and Dan Ila gave the poorest performance when unsprayed”
Claim · model-written summary
IT86D-719, IAR-48 and Dan Ila gave the poorest performance in unsprayed cowpea.
- Taxon
- cowpeaVigna unguiculatat0
- Material
- IT86D-719, IAR-48 and Dan Ilae5
- Outcome
- poorest performancee5
- Qualifier
- when unsprayede5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e5“IT90K-277-2, IT93K-734, IT93K-452-1 and IT93K-513-2 performed best whereas IT86D-719, IAR-48 and Dan Ila gave the poorest performance when unsprayed”
Claim · model-written summary
Two insecticide sprays of Cypermethrin + dimethoate increased cowpea grain yields considerably from 225 to 900 kg ha-1 for cowpea planted in July and August.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- Two insecticide sprays of Cypermethrin + dimethoatee6
- Outcome
- grain yieldse7
- Direction
- increasede7
- Value
- from 225 to 900 kg ha-1e7
- Qualifier
- for cowpea planted in July and Auguste7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e6“Two insecticide sprays of Cypermethrin + dimethoate”
e7“increased grain yields considerably from 225 to 900 kg ha-1 for cowpea planted in July and August”
Claim · model-written summary
Insecticide application was more profitable for cowpea planted in late July and August than when planted in June and early July.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- insecticide applicatione7
- Outcome
- profitablee7
- Direction
- moree7
- Qualifier
- Cost-benefit analysise7
- Comparator
- when planted in June and early Julye7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e7“Cost-benefit analysis indicated that the insecticide application was more profitable for cowpea planted in late July and August than was the case when planted in June and early July”
Claim · model-written summary
Early maturing elite cultivars could escape economic damage from post-flowering pests when cowpea is planted early in the season.
- Taxon
- cowpeaVigna unguiculatat0
- Treatment
- when cowpea is planted early in the seasone7
- Interactor
- post-flowering pestse7pest
- Outcome
- escape economic damagee7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“cowpea insect pests”
e7“This seems to suggest that early maturing elite cultivars could escape economic damage caused by post-flowering pests when cowpea is planted early in the season”
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