INTRODUCTION
Plant growth regulators and pesticides are being applied separately for enhancing plant growth and for the control of insect pests and diseases, respectively. This becomes rather costly and also involves more of labour and time in applying. If plant growth regulators and insecticides are applied in association in a single operation it could be cheaper in the view of farmers. Since the pesticides and plant growth regulators are chemically different in nature, their compatibility may pose a problem. Hence it requires thorough investigation before its widespread commercial application. Mixture of two pesticides may produce a greater insecticidal action than the sum of their individual components by exhibiting synergism[1], thus minimising the pesticidal load on the environment. Mixtures may also bring about significant cost efficiency[2].
The fungicide (hexaconazole) and insecticide (monocrotophos) were found to have synergistic effect and exerted high efficiency towards pests and disease of grapes[3]. Padmaja and Kameshwara Rao[4] reported that monocrotophos and carbendazim, carbaryl and mancozeb were highly compatible and recorded higher mortality than their individual insecticidal spray. The combination of herbicides fluchloralin and alachlor with carbendazim, benomyl and carboxin altered their fungicidal action and showed synergistic effect against Fusarium oxysporum, Sclerotium rolfsii, A. brassicicola and Colletotrichum capsici[5].
All the fungicides and their combination with the insecticide were effective in reducing the sheath blight disease and indicated the compatibility nature[6]. Hence, the present study was formulated to evaluate the possibility of compatibility of Atonik with insecticide and fungicide in cotton and tomato.
MATERIALS AND METHODS
Insecticide: The compatibility of Atonik with insecticides in tomato and cotton, a pot culture study was conducted during 2002-2003 at the glasshouse of the Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore, India.
Tomato: The experiment consisted of seven treatments with ten replications
in Randomized Block Design. The treatment details are as follows:
| T1 |
= |
Atonik 0.1%+Monocrotophos 2 ml L-1 |
| T2 |
= |
Atonik 0.2%+Monocrotophos 2 ml L-1 |
| T3 |
= |
Atonik 0.4%+Monocrotophos 2 ml L-1 |
| T4 |
= |
Atonik 0.8%+Monocrotophos 2 ml L-1 |
| T5 |
= |
Monocrotophos 2 ml L-1 alone |
The first round of spraying was given at 45 days after planting and the spraying was repeated once at 15 day intervals as per the treatment schedule. The incidence of whitefly and aphids was visually recorded before treatment and 1, 3, 5 and 7 days after treatment on six leaves per plant, two each from top, middle and bottom portions of ten plants and the population was arrived at for each treatment, according to the method of Sudhakar et al.[7] for whitefly and Uthamasamy et al.[8] for aphid as described earlier.
Yield and yield components namely fruit set percentage, fruit weight and yield per plant were recorded on ten plants.
Cotton: The experiment consisted of six treatments with ten replications
in Randomized Block Design. The treatment details were as follows:
| T1 |
= |
0.1% Atonik+confidor 0.2 ml L-1 |
| T2 |
= |
0.25% Atonik+confidor 0.2 ml L-1 |
| T3 |
= |
0.5% Atonik+confidor 0.2 ml L-1 |
| T4 |
= |
Confidor 0.2 ml L-1 alone |
The first round of spraying was given at 25 days after planting and the spraying was repeated once at 15 day intervals. The population of whitefly and aphid was recorded prior to application and 1, 3, 5 and 7 days after spraying. The population of both nymphs and adult whiteflies was counted every morning when the insects were inactive. The population count was recorded on top two, two middle and one bottom leaves in each of ten tagged plants. Finally mean number of whiteflies per ten plants was calculated[7]. The population count of aphid was recorded on ten plants. In each plant, three leaves one each from the top, middle and bottom regions of the plant were examined for the presence of aphids and the total number of aphids per 10 plants was calculated[8].
Yield and yield components namely number of bolls, boll weight, seed cotton yield and fertility co-efficient were recorded on ten plants.
The observations on phytotoxicity in cotton and tomato were made on 1, 3 and 7 days after each application by recording injury to leaf tip and leaf surface, wilting, vein clearing, necrosis, epinasty and hyponasty and graded by adopting the following scale[9].
Fungicide: Compatibility of Atonik with fungicides was tested using carbendazim and fytolon to check the growth of four pathogens viz., Fusarium oxysporum f. sp. asinfectum and Colletotrichum capsici for cotton and Alternaria alternata and Botrysis cinerea for tomato by using poisoned food technique[10] with three replications.
Cotton:
| T2 |
= |
0.1% Atonik+200 mg carbendazim |
| T3 |
= |
0.25% Atonik+200 mg carbendazim |
| T4 |
= |
0.5% Atonik+200 mg carbendazim |
| T5 |
= |
40 ppm NAA+200 mg carbendazim |
Tomato:
| T2 |
= |
0.1% Atonik+200 mg fytolon |
| T3 |
= |
0.2% Atonik+200 mg fytolon |
| T4 |
= |
0.4% Atonik+200 mg fytolon |
| T5 |
= |
0.8% Atonik+200 mg fytolon |
| T6 |
= |
50 ppm PCPA+200 mg fytolon |
The radial mycelial growth of the fungus and per cent inhibition in the growth of fungus was studied according to Varalakshmi et al.[3]. The percent growth inhibition was calculated as per Vincent[11].
RESULTS
Insecticides
Tomato: Effect of Monocrotophos with Atonik against tomato whitefly
revealed that the pre-treatment population count recorded prior to first spray
ranged between 13.00 and 14.67 with non-significant result. One day after the
spray 1st, lowest population was observed in T5 (4.67) followed by
T4 (5.33), both of them were on par. Atonik 0.25% alone (T6)
recorded a population of 12.00, whereas the control had the highest population
count of 16.33. At 5 day after treatment, T2, T3, T4
and T5 were on par with each other and T4 and T5
recorded a population count of one per 10 plants. At 7 DAT, the population of
whitefly increased slightly irrespective of the treatments. At this time, maximum
population was observed in T7 (16.33), followed by Atonik 0.25% alone
(10.67). T3, T4 and T5 were on par (Table
1).
After 2nd spray, the population of whitefly decreased from 1 DAT to 5 DAT. The pretreatment count ranged between 21.00 and 22.67 and the treatment did not differ significantly. On the 5th day after treatment, the lowest population was observed in T4 and T5 (1.0). The treatments, T4 and T5 were on par and T1 and T3 were on par with each. The best treatments T4 and T5 recorded a control of 96.1%, followed by next best T3 (91.0%). Prior to spray 1st, the population count of aphid ranged between 35.33 and 38.00. Here also, the difference was non-significant. After application of chemical, the population reduced drastically at 1 and 3 DAT, the reduction extended upto the 5th day after application. At that time, control had a population of 37.0, followed by Atnoik alone (T6) (Table 2). Maximum control was achieved in T5 (monocrotophos 2 ml L-1 alone) to a tune of 90.0%, followed by T4 (monocrotophos 2 ml L-1 +Atonik 0.8, 89.1%). Atonik alone had reduced the population by 16.2% over control. The same trend was also observed in spray 2nd also. T5 showed a % decrease of 72.7, followed by T1 (60.2%). Minimum population was observed on the 5th DAT. Atonik alone reduced the population by 9.0% over T7. On the 5th DAT, during 2 spray T1, T2, T3 and T4 were on par.
Cotton: Application of Confidor had a profound effect on the whitefly population reduction after 1st and 2nd sprays. The population reduction was drastically reduced after first day of application and the effect was maintained for two more days due to both the sprays. In both the sprays, T4 was the best. During 1st spray on the 3rd day after application, treatments T1, T2, T3 and T4 were on par with each other (Table 3). The other treatments (T5 and T6) were significant at all days at both the stages. After 1st spray, the treatments T1, T2, T3 and T4 showed a decrease of 89.5, 92.1, 92.1 and 92.1%, respectively over control at 3rd DAT, whereas after 2nd spray T1, T2 and T3 recorded a% reduction of 86.0, 86.0 and 88.0%, respectively over control. The best treatment T4 had a reduction of 92.1 and 94.0% over control at 1st and 2nd stages, respectively. Atonik reduced the population by 52.6 and 56.0% over control after 1st and 2nd sprays, respectively.
The pre-treatment population count of aphid ranged between 63.00 and 65.67% (Table 4). After application of chemical, the population reduced drastically at 1 and 3 DAT and the reduction extended upto 5 days after application. At that time, control had a population of 61.67, followed by T5 (46.67). Maximum control was achieved in T4 to a tune of 92.4%, followed by T1 and T2 (90.2). Atonik alone had reduced the population by 24.3% over control. The same trend was also followed in the 2nd spray also. T3 and T4 treatments showed a % reduction of 94.7, followed by T1 and T2 (91.6%). Minimum population was observed on 5th day after treatment. Atonik alone reduced the aphid population by 24.3 and 38.5% over control during 1st and 2nd sprays, respectively. On the 5th day after treatment, during 1st and 2nd sprays, T1, T2, T3 and T4 were on par.
Fungicide
Cotton: Among the treatments imposed maximum control of Fusarium
oxysporum f.sp. vasinfectum was observed in the treatment T3,
T4, T5 and T6 which recorded a decrease of
100.0% over control. The corresponding decrease in T2 was 92.3. The
treatments T3, T4, T5 and T6 were
on par with each other. Effect of Atonik with carbendazim on control of C.
capsici revealed that maximum inhibition of growth was achieved in treatment
T4 and T5 (87.3%) over control. This was followed by T6
and T3 with the reduction of 87.1 and 85.8%, respectively over control.
The treatments T5 and T6 were found to be on par whereas
the other treatments differed significantly (Table 5).
Tomato: Among the treatment exercised, maximum inhibition of Alternaria alternate growth was achieved in T1 (100.0%) and was followed by T6 (87.6%). The treatments differed significantly among themselves. The maximum reduction in the growth of Botrytis cinerea was seen in T4, T5, T6 and T7 treatments with a percent reduction of 100.0 over control. The other treatments differed significantly (Table 5).
Yield components of tomato: Among the treatments imposed, maximum number of fruit clusters per plant was observed in T3 (Monocrotophos 2 ml L-1+Atonik 0.4%), followed by T4, T2 and T6. The difference between the treatments was significant. Among the treatment imposed, maximum number of fruits per plant was observed in T3 followed by T4. The % increase was 16.44 and 11.80 over control. The treatments differed significantly among themselves. Fruit weight was maximum in T4 (66.32), followed by T3 (64.86). These treatments recorded an increase of 33.0 and 30.0% over control, respectively. The treatments differed significantly for fruit weight. Among the treatments imposed, T3 recorded the highest yield per plant followed by T4 and T7 recorded the lowest yield per plant. The percent increase was 37.7 (T3) and 36.4 (T4) over control. The mean difference between the treatments was found to be significant (Table 6).
Yield components of cotton: Maximum flower number was attained in the treatment T6 (39.48), followed by T4 (38.42).
| Table 1: |
Compatibility of Atonik with monocrotophos against tomato
whitefly-1st and 2nd spray |
|
| * - Pre-treatment count, |
** - Mean of three replications, |
Number in parentheses indicates square root transformed value |
| Table 2: |
Compatibility of Atonik with Monocrotophos against tomato
aphid-1st and 2nd spray |
|
| * - Pre-treatment count, |
** - Mean of three replications, |
Number in parentheses indicates square root transformed value |
| Table 3: |
Compatibility of Atonik with Confidor against cotton whitefly-1st
and 2nd spray |
|
| * - Pre-treatment count, |
** - Mean of three replications, |
Number in parentheses indicates square root transformed value |
| Table 4: |
Compatibility of Atonik with Confidor against cotton aphid-1st
and 2nd spray |
|
| * - Pre-treatment count, |
** - Mean of three replications, |
Number in parentheses indicates square root transformed value |
| Table 5: |
Compatibility of Atonik with fungicides on control of pathogens
of cotton and pathogens of tomato |
|
|
| Table 6: |
Compatibility of Atonik with Monocrotophos and Confidor on
yield components at different growth stages in tomato var PKM 1 and cotton
var MCU 12 |
|
|
| Table 7: |
Phytotoxicity grade of confidor and combination of Atonik
and monocrotophos and combination of Atonik in cotton var MCU 12 and tomato
var PKM 1 |
|
| * - Mean of three samples |
A–Phytotoxicity, B–Scorching, C–Vein clearing,
D – Epinasty, H – Hyponasty, F – Leaf injury |
The treatments, T2, T3 and T5 were on par with each other. The mean difference of the treatments was found to be significant. Maximum number of bolls was observed in T2 (15.84), followed by T3 and T5 (14.00). The mean difference of the treatments was significant. The lowest boll number was observed in control (12.00). Among the treatments, the mean difference in boll weight was found to be significant. T2 had a slightly higher value (4.12) followed by T3 (4.10). Maximum yield per plant was attained in the treatment T2 (48.36), followed by T5 (46.36). The best treatment recorded an increase of 48.6% over control. The other treatments, T1, T3, T4 and T5 showed an increase of 15.9, 30.7, 4.05 and 42.4%, respectively over control (Table 6).
Phytotoxicity grade of confidor and monocrotophos and their combination with atonik: Among the treatments imposed all the treatments at 1, 3 and 5 days after treatment showed zero grades, for both cotton and tomato.
DISCUSSION
Insecticide: Application of confidor at 2 ml L-1 significantly reduced the whitefly and aphid population in cotton. When Atonik was mixed with confidor, it exhibited significant reduction in the population of whitefly and aphid. When Atonik alone was sprayed, it reduced the pest load significantly over control, but the reduction was very meager. Further, the cumulative effect was more than the single application. This might be due to the nature of pest damage and its manifestation. Similar type of result was also reported by Lingappa et al.[12] in cotton by using various insecticides. Dandale et al. [13] observed the same result that Imidacloprid, as seed dresser insecticide was effective against sucking pests of cotton. Humic acid (a phenolic acid mixture) as a tank mixture with fenvalerate significantly mitigated the problems of whitefly resurgence[14]. This indicates that Atonik, being a phenolic compound, can be mixed with other insectides for efficient control of insects as well as for better yield as evident from the study.
In tomato, the same trend was found, (i.e.) application of monocrotophos alone significantly reduced the whitefly and aphid population. When Atonik was mixed with monocrotophos, the reduction of population of whitefly and aphid was evident. This indicates its compatibility nature with monocrotophos. The above result was similar to the finding of Reddy and Joshi[15], that application of Endosulfan in combination with Planofix (NAA) gave higher yield and best pest control in brinjal. The results of the present study also are in agreement with the findings of Srinivas and Peter[16], Walunj et al.[17] and Anil Kumar et al.[18] in brinjal. Atonik alone also exhibited mild insecticidal property (as evidenced by population of pest).
The increased cotton yield in confidor (Imidacloprid) and Atonik+confidor treatments as observed in the present study may be due to the fact that imidacloprid enhances crop growth and leaf area as reported by Dandale et al.[13] and the auxin like activity of Atonik[19]. The same result was also observed by Graham[20], Almand[21] and Attique and Gaffar[22]. Phytotonic effect of imidacloprid treated plants was observed and it was positively correlated with plant height, growth and yield components in cotton[23].
The tomato plant, treated with monocrotophos along with Atonik produced significantly higher yield than other treatments and Atonik sprayed alone. The results of present study corroborated with the finding of Praveen and Dhandapani[24], Chitra et al.[25].
Fungicide: From the results of the experiments with cotton and tomato, it can be inferred that there is compatibility between Atonik and carbendazim or fytolon. Atonik, being a nitrophenol, may undergo enzymatic hydrolysis to yield the toxic compound, which exerts a negative environment in the fungus[26]. These toxic compounds may induce the swelling of hyphal tips and germ tubes, often resulting in lysis. Plant growth hormones and their synthetic analogues are well known as antagonists of fungal disease[27]. The auxin, by their effects on cell wall structure, might be particularly active against wilt diseases. Since Atonik exhibits auxin like activity as evidenced from the present study it can be concluded that Atonik challenges the growth of fungus by the above said mechanism[28]. The auxin like compounds like amino trichloro phenyl acetic acid[28], indolyl acetic acid, naphthalene acetamide[29] and 2, 3, 6-trichloro phenyl acetic acid[27] antagonize the effects of infection by C. ulmi on elm, Ceratocystis fagacearum on oak and Verticillium alboatrum on tomato. This may be direct evidence showing that auxin are involved in disease control as also observed in the present study.
Thus, it is concluded that the insecticides did not alter the plant growth promoting activity of Atonik as evidenced by increased yield. The efficacies of insecticides were also not hampered by Atonik as shown by reduced pest population. Monocrotophos and confidor treatments either alone and/or in combination with Atonik showed only zero grades of phytotoxicity symptoms in tomato and cotton.