Comparison of ULV with conventional spraying on cotton in Pakistan

CROP PROTECTION (1983) 2 (2), 231-234

C o m p a r i s o n o f U L V with c o n v e n t i o n a l spraying on cotton in Pakistan M. R. ATTIQUE AND M. A. SHAKEEL

Entomology Division, Central Cotton Research Institute, Multan, Pakistan ABSTRACT. ULV and conventional low-volume spraying were compared

using ULV and e.c. formulations of deltamethrin, cypermethrin and triazophos to control cotton pests. Both spraying techniques were effective, but Bemisia spp. were controlled better with the low-volume aqueous sprays. The ULV sprayer was much cheaper to use than the conventional knapsack sprayer and covered a five- to six-fold greater area daily.

Introduction Cotton is damaged by a number of insect pests in Pakistan (Chaudry, 1973; Yunas, 1973) and yields are therefore low. The damage varies from year to year, but generally ranges from 30~o to 40~/o (Ahmed, 1980). Some insecticides have been used, but applications with knapsack and compression sprayers on small farms during hot weather have not been very acceptable to farmers. Ultra-low-volume (ULV) spraying with formulations of low volatility has been adopted in a number of countries, particularly in several African countries (Matthews, 1971; 1973). Studies were therefore undertaken to compare the ULV technique with conventional low-volume spraying and also to determine the economics of ULV spraying. This note reports a trial at the Central Cotton Research Institute, Multan, Pakistan, during the 1980-81 crop season. Materials and methods The three insecticides listed in Table 1 were used both as ULV formulations applied at 2.5 f/ha, and as emulsifiable concentrates (e.c.) diluted in water, applying 350-500 E/ha, according to the crop height. Three replications of these treatments, and of an untreated control, were used on a 1 ha field of cotton (Gossypium hirsutum), variety MNH93. ULV sprays were applied by a hand-held battery-operated spinning-disc sprayer (Turbair X) with a typical disc speed of 8000 rev/min. Because most farmers use hand-operated knapsack sprayers, the other method of application was with one such 0261-2194/83/02/0231-04503.00 © 1983Butterworth&Co (Publishers)Ltd

232

ULV vs conventional spraying of cotton in Pakistan TABLE 1. Formulations and doses of insecticides used

Formulation

Dose (a.i.) (ml/ha)

Chemical name

Common name

(S)-~-cyano-3-phenoxybenzyl (1R)-cis-3(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate

deltamethrin

O, O-diethyl O-l-phenyl-l,2,4-triazol-3-yl phosphorothioate

triazophos

25 40

ULV e.c.

620 1000

(RS)-a-cyano-3-phenoxybenzyl (1RS)-cis, trans-3-(2,2-dichlorovinyl-2,2-dimethylcyclopropanecarboxylate

cypermethrin

3 10

ULV e.c.

74 62

0"5 ULV 2.5 e.c.

12 15

sprayer, the CP3, with a capacity of 20 f, which was fitted with a plastic hollow-cone spray nozzle and which operated at a pressure of 40 p.s.i. (lbf/in 2) ~ 276 kPa. Each experimental plot consisted of 10 rows of cotton, 28.5 m in length, with an additional 10 rows as a guard between plots to minimize the effects of spray drift. Seven sprays were given at 10-day intervals starting from the last week of July to the end of September. The speed required for the application of U L V formulations in each treatment was predetermined. The operator tried to maintain a walking speed of about 1 m/s for the U L V treatments, with a swath width of 4 m, i.e. five rows. The conventional sprays were applied to obtain thorough coverage of the plant. Data relating to pests and crop development were recorded weekly. Results and discussion Both techniques of spraying effectively controlled the cotton pests (Table 2). The numbers of jassids (Empoasca spp.) and whiteflies (Bemisia spp.) were significantly reduced by both types of spray formulations. Triazophos was better than the pyrethroids in controlling whiteflies. The conventional volume sprays of the pyrethroids gave a significantly better control of whitefly than did the U L V formulations. These results are in agreement with those of Singh and Khangura (1973) and of Ruscoe (1980). Populations of mites (Tetranychus spp.) were very much higher on the plots treated with pyrethroids than on the controls and the plots treated with triazophos. The plots treated with deltamethrin e.c. had significantly more mites compared with the other treatments. All treatments gave acceptable control of bollworms, which were mainly Earias spp. Triazophos-treated plots yielded more seed cotton than those on which pyrethroids were used: this may be attributable not only to the flare-up of mites, but also to the high populations of whitefly, especially where deltamethrin U L V was applied. There was a marked difference in the initial cost and rate of working of the two spraying methods. The cost of the knapsack sprayer was about 50% higher than that of the spinning-disc U L V sprayer: the latter sprayer covered 5-6 ha/day, whereas

damage caused bollworms

by

9.00 1.80 0.15 0-08 4.20 0"55 12.80 0.53

Jassids (No./lea0

0"15 0.19

0.20 0-16

0.25 0"27

0-51 0.044

deltamethrin ULV deltamethrin e.c.

triazophos ULV triazophos e.c.

cypermethrin ULV cypermethrin e.c.

Untreated control SE+_

11.7 2.99

80-5 89.2

1.6 0-0

.... 47"5 227.0

2.49 2.08

0-12 0.09

0.47 0.29

0.24 0.15

2.0 0.16

0.1 0.0

0-5 0.0

0.0 0.0

1895 397

1956 2060

2822 2972

1577 2309

Yield of seed cotton Whitefly Mites (kg/ha) (No./leaf) (No./leaf) on immature fruit on mature fruit

Percentage

Average insect-pest population, bollworm damage and yield of seed cotton

Insecticide

TABLE 2.

I-o G.a

Z

234

UL V vs conventional spraying o f cotton in Pakistan

the knapsack sprayer covered only 1 ha/day. In addition, the cost of labour was at least five times greater for the knapsack sprayer than when the U L V sprayer was used. T h e amount o f active ingredient applied per hectare tended to be higher when emulsifiable concentrates were used, thus increasing the cost o f the chemical per hectare. T h e e.c. formulations cost about 24% more per hectare than the U L V formulations, i.e. 275 rupees (US$27.5) for e.c. instead of 222 rupees (US$22.2) for U L V formulations per hectare. W h e n all these factors were taken into account, the spinning-disc U L V sprayer was m u c h more economical to use than a conventional knapsack sprayer, but great care is needed in the choice of a suitable insecticide as yields will be reduced if mite populations increase too early in the season.

References AHMED,Z. (1980). Incidence of major cotton pests and diseases in Pakistan with special reference to pest management. In: Proceedings, 1st International Consultation on Cotton Production Research with focus on the Asian Region, Manila, Philippines, 17-21 November 1980, pp. 156-179 CHAUDRY,G.Q. (1973). Cultural control of cotton pests. In: Proceedings of Seminar on Insect Pests of Cotton, 28-29 April 1973, Cotton Research Institute, Multan, pp. 82-86. Organized by Pakistan Central Cotton Committee, Moulvi Tamizuddin Khan Road, Karachi. MATTHEWS, G.A. (1971). Ultra low volume spraying of cotton--a new application technique. In: Cotton Handbook of Malawi, Amendment No. 2/71, pp. 1-11. Malawi: Agricultural Research Council. MATTHEWS,G.A. (1973). Ultra low volume spraying of cotton in Malawi. Part I. Effect of dosage swath and volume of application. Cotton Growing Review 50, 242-267. RuscoE, C.N.E. (1980). Pyrethroids as cotton insecticides. Outlook on Agriculture 10, 167-175. SINGH,H. ANDKHANGURA,J.S. (1973). Efficacyof dilute and concentrated sprays for the control of cotton pests. Cotton Growing Review 50, 72-78. YOUNAS,M. (1973). Threshold of economicinjury of insects and mite pests of cotton. In: Proceedings of Seminar on Insect Pests of Cotton, 28-29 April 1973, Cotton Research Institute, Multan, pp. 61-66. Organized by Pakistan Central Cotton Committee, Moulvi Tamizuddin Khan Road, Karachi. Accepted 30 May 1982