Evaluation of oomycete-specific fungicides and application strategies for controlling fruit rot disease on arecanut (Areca catechu L.)

Figures & data

Figure 1. A schematic diagram representing randomization and assigning 13 treatments in RCBD design with three replications under field conditions.

Table 1. Oomycete-specific fungicidal products for the control of fruit rot disease (FRD) of arecanut during 2018 and 2019 in the Malnad region, Karnataka, India.

Active ingredient	Registered concentration	Fungicidal formulation^a	Fungicide symbol	Manufacturer	FRAC group^b
Famoxadone + Cymoxanil	2–2.5 mL L^−1	SC	FAM CYM	DuPont	27
Kresoxymethyl	1.0 mL L^−1	SC	KRES	Rallis India	11
Mandipropamid	5.0 mL L^−1	SC	MAND	Syngenta	40
Dimethomorph + Mancozeb	2–2.5 g L^−1	WP	DIM MZB	Syngenta	40 M03
Ametoctradin + Dimethomorph	2–2.5 mL L^−1	SC	AMT DIM	BASF	45 40
Cymoxanil + Mancozeb	2–2.5 g L^−1	WP	CYM MZB	DuPont	27 M03
Iprovalicarb + Propineb	2–2.5 g L^−1	WP	IPR PROP	Bayer	40 M03
Metiram + Pyraclostrobin	2–2.5 g L^−1	WG	MET PYRA	PI Industries	M03 11
Copper hydroxide	3.0 g L^−1	WP	COPH	DuPont	M01
Metalaxyl + Mancozeb	2–2.5 g L^−1	WP	METL MZB	Syngenta	04 M03
Bordeaux mixture	1%	SL	BM	–	M01
Fosetyl-Al	3.0 L^−1	WP	FSAL	Bayer	P07 33

^a WP, wettable powder; WG, water dispersible granule; SL, soluble liquid; SC, suspension concentrate.

^b Fungicide Resistance Action Committee (FRAC), 2022. List of fungicides’ common names.

Starting time: The first spray was initiated at the start of the monsoon on immature nuts.

Application timing: Pre-monsoon, mid-monsoon, fag-end of monsoon (all the fungicides were tested at three application strategies depending on the moment of infection).

No. of sprays: Three (the first spray at the 30th of May, the second spray was on the 15th of July and the third was 30th of August during monsoon season at 30–45 days intervals).

Table 2. The following rating scale was utilized to estimate the percent disease severity of FRD on arecanut.

Rating scale	Description
1	1–10% fallen nuts per palm
2	11–25% fallen nuts per palm
3	26–50% fallen nuts per palm
4	51–75% fallen nuts per palm + spread of the disease to bunch stalk
5	76–100% fallen nuts per palm + spread of the disease to the main stalk of the bunch
6	Complete crown death (CCD)

Figure 2. Fruit rot disease (FRD) severity (green colored) and reduction in severity or control efficiency (%, yellow colored) of different contact and systemic oomycete-specific fungicides in 2018 and 2019. The error bars indicate the standard error of the mean.

Figure 3. Fruit rot disease (FRD) incidence (green colored) and the corresponding reduction in incidence or control efficiency (%, yellow colored) of different contact and systemic oomycete-specific fungicides in 2018 and 2019. The error bars indicate the standard error of the mean.

Figure 4. CFNR (green colored) and the corresponding reduction in incidence or control efficiency (%, yellow colored) of different oomycete-specific fungicides in 2018 and 2019. The error bars indicate the standard error of the mean.

Table 3. FRD severity, control efficiency and other corresponding statistics of 12 fungicides evaluated at pre-monsoon time for control of FRD in 2018 and 2019.

Fungicides	FRDseverity^a	CLLower^b	CLUpper^b	CE^c
BM	6.34a	−9.43	22.12	78.04
MAND	7.00a	−8.77	22.81	75.76
METL_MZB	9.95b	−5.82	25.70	65.54
FSAL	11.02b	−4.74	26.83	61.84
KRES	14.91c	−0.86	30.77	48.37
CYM_MZB	14.96c	−0.80	30.78	48.19
AMT_DIM	16.33c	0.55	32.10	43.45
MET_PYRA	16.51c,^d	0.74	32.32	42.83
DIM_MZB	16.68c,^d	0.90	32.56	42.24
FAM_CYM	17.28c,^d	1.51	33.10	40.16
COPH	17.48c,^d	1.70	33.28	39.47
IPR_PROP	19.13^d	3.35	34.91	33.76
Control	28.88^e	13.15	44.60	–

^a Mean severity level recorded due to FRD in 2018 and 2019. Treatment means with different letters are significantly different according to Tukey–Kramer’s test (p < 0.05).

^b Lower and upper limits of 95% confidence interval around FRD severity.

^c Percentages of control efficiency of fungicides calculated concerning the UTC.

Table 4. FRD severity, control efficiency and associated parameters for 12 fungicides tested during the Mid-monsoon period for control of FRD in 2018 and 2019.

Fungicides	FRDseverity^a	CLLower^b	CLUpper^b	CE^c
BM	10.20a	−11.51	31.90	66.11
MAND	10.90a	−10.80	32.60	63.78
FSAL	12.80^ab	−8.92	34.40	57.47
METL_MZB	14.20bc	−7.51	35.80	52.82
MET_PYRA	14.70bc	−7.01	36.40	51.16
CPOH	15.80cd	−5.93	37.40	47.50
AMT_DIM	16.30cd	−5.35	38.00	45.84
KRES	16.40cd	−5.27	38.10	45.51
DIM_MZB	16.50cd	−5.18	38.20	45.18
FAM_CYM	17.50^de	−4.19	39.20	41.86
CYM_MZB	18.50^de	−3.18	40.20	38.53
IPR_PROP	19.70^e	−1.99	41.40	34.55
Control	30.10^f	8.41	51.80	–

^a Mean severity level recorded due to FRD in 2018 and 2019. Treatment means with different letters are significantly different according to Tukey–Kramer’s test (p < 0.05).

^b Lower and upper limits of 95% confidence interval around FRD severity.

^c Percentages of control efficiency of fungicides calculated with the UTC.

Table 5. FRD severity, control efficiency and associated parameters for 12 fungicides were evaluated during fag-end monsoon for control of FRD in 2018 and 2019.

Fungicides	FRDseverity^a	CLLower^b	CLUpper^b	CE^c
BM	28.50a	−42.39	99.40	78.07
MAND	31.50a	−39.42	102.40	75.76
METL_MZB	44.80b	−26.14	115.70	65.53
FSAL	49.60b	−21.31	120.50	61.84
KRES	67.10c	−3.81	138.00	48.38
CYM_MZB	67.30c	−3.57	138.20	48.23
AMT_DIM	73.50c	2.57	144.40	43.46
MET_PYRA	74.30cd	3.44	145.30	42.84
DIM_MZB	75.10cd	4.15	146.00	42.23
FAM_CYM	77.80cd	6.87	148.70	40.10
COPH	78.60cd	7.74	149.50	39.53
IPR_PROP	86.10^d	15.17	157.00	33.76
Control	130.00^e	59.05	200.90	–

^a Mean severity level recorded due to FRD in 2018 and 2019. Treatment means with different letters are significantly different according to Tukey–Kramer’s test (p < 0.05).

^b Lower and upper limits of 95% confidence interval around FRD severity.

^c Percentages of control efficiency of fungicides calculated in relation to the UTC.

Table 6. Variations in FRD severity and control efficiency between the time of fungicidal application for control of FRD in 2018 and 2019.

Fungicides	FRDseverity^a	CLLower^b	CLUpper^b	p Value
Pre-monsoon	12.97a	−101.15	178.80	≤0.05
Mid-monsoon	36.03b	−32.02	247.90	≤0.05
Fag-end monsoon	50.54c	11.53	291.50	≤0.05

^a Mean severity level recorded due to FRD in 2018 and 2019. Treatment means with different letters are significantly different according to Tukey–Kramer’s test (p < 0.05).

^b Lower and upper limits of 95% confidence interval around FRD severity.

FRAC. (2022). FRAC Code List 2021: Fungicides Sorted by Mode of Action. http://www.phi-base.org/images/fracCodeList.pdf (accessed on 31 July).

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Data availability statement

The data that support the findings of this study are available from the corresponding author, [Balanagouda Patil], upon reasonable request.