SOURCES AND CONCENTRATIONS OF CUPRIC FUNGICIDES FOR THE CONTROL OF CITRUS BLACK SPOT<sup>1</sup>

FRANCO, DANILO; GOES, ANTONIO DE; PEREIRA, FERNANDA DIAS

doi:10.1590/1983-21252020v33n101rc

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Agronomy • Rev. Caatinga 33 (1) • Jan-Mar 2020 • https://doi.org/10.1590/1983-21252020v33n101rc copy

SOURCES AND CONCENTRATIONS OF CUPRIC FUNGICIDES FOR THE CONTROL OF CITRUS BLACK SPOT¹

FONTES E CONCENTRAÇÕES DE FUNGICIDAS CÚPRICOS NO CONTROLE DA MANCHA PRETA DOS CITROS

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

Citrus black spot (CBS) is a severe disease for citriculture in the São Paulo State, Brazil. Part of its management is focused on chemical control using cupric fungicides and strobilurins. The objective of the present work was to evaluate the efficacy of three sources and three concentrations of cupric fungicides (copper hydroxide, copper oxychloride and cuprous oxide). Orange fruits of the Pera cultivar were bagged in the plants and the treatment with cupric fungicide was applied. The fruits were inoculated (by spray) with Phyllosticta citricarpa (1×10⁴ conidia mL^-1) after 0, 7, 14, 21, and 28 days, and bagged again. The evaluation of incidence and severity was did at the harvest time of fruits. A second experiment was conducted under natural infection with the same treatments, consisting of application of fungicides at the stages F1 (petal fall) and F2 (fruits with diameter of 1 cm), using mechanized sprayer with mean flow of 7.35 L solution plant^-1. Subsequently, all treatments received four applications of azoxystrobin (30 g ha^-1), plus mineral oil at 0.25%. Four monthly evaluations were done to determine the CBS incidence and severity. The initial applications with cupric fungicides are essential for the control of CBS; the fungicide copper hydroxide showed the best control of CBS with the lowest rate of metallic copper (43.7 g of Cu⁺⁺ 100 L^-1) in both experiments, regardless of the conduction conditions.

Keywords:
Citrus sinensis; Phyllosticta citricarpa; Metallic copper

Treatments	Concentration	Rate per 100 liters of solution
	Concentration	Formulated
	g ^kg^-1	Product	Metallic Copper
Copper hydroxide (538 g kg^-1)	538	125.0	43.7
Copper hydroxide (538 g kg^-1)	538	100.0	35.0
Copper hydroxide (538 g kg^-1)	538	75.0	26.2
Copper oxychloride (840 g kg^-1)	840	200.0	100.8
Copper oxychloride (840 g kg^-1)	840	180.0	90.7
Copper oxychloride (840 g kg^-1)	840	135.0	68.0
Cuprous oxide (860 g kg^-1)	860	120.0	90.0
Cuprous oxide (860 g kg^-1)	860	75.0	56.3
Cuprous oxide (860 g kg^-1)	860	56.3	42.2
Control

Sources of variation		Incidence (%)		Disease index
Treatments	Rate (g of metallic copper 100 L^-1)
1. Copper hydroxide (538 g kg^-1)	43.7	16.9	A	0.22	a
2. Copper hydroxide (538 g kg^-1)	35.0	24.5	b	0.31	b
3. Copper hydroxide (538 g kg^-1)	26.2	26.5	b	0.34	b
4. Copper oxychloride (840 g kg^-1)	100.8	14.7	a	0.19	a
5. Copper oxychloride (840 g kg^-1)	90.7	13.0	a	0.17	a
6. Copper oxychloride (840 g kg^-1)	68.0	32.5	c	0.41	c
7. Cuprous oxide (860 g kg^-1)	90.0	17.9	a	0.24	a
8. Cuprous oxide (860 g kg^-1)	56.3	20.8	b	0.27	b
9. Cuprous oxide (860 g kg^-1)	42.2	38.9	c	0.49	c
10. Control		54.0	d	0.68	d
F Test		13.612		18.058
Days after application
0		18 .7	a	0.25	a
7		25.7	b	0.33	b
14		26.5	b	0.34	b
21		31.2	b	0.40	b
28		27.8	b	0.35	b
F Test		5.047	**	4.996	**
Interaction (Treatment × Days after application)
F Test		1.052	ns	1.103	ns
CV (%)		32.88		10.87

Treatments	Rate	Incidence
	Rate	Evaluation 1	Evaluation 2	Evaluation 3	Evaluation 4
	g 100 L^-1	08/10/2016	09/08/2016	10/06/2016	11/14/2016
Copper hydroxide (538 g kg^-1)	125.0	22.0 a	33.1 a	46.0 a	67.3 a
Copper hydroxide (538 g kg^-1)	100.0	32.8 b	42.0 a	52.3 a	81.5 b
Copper hydroxide (538 g kg^-1)	75.0	42.3 b	43.8 a	46.3 a	77.0 a
Copper oxychloride (840 g kg^-1)	200.0	23.0 a	36.5 a	51.0 a	73.0 a
Copper oxychloride (840 g kg^-1)	180.0	22.0 a	36.7 a	52.8 a	73.0 a
Copper oxychloride (840 g kg^-1)	135.0	40.3 b	48.0 b	56.5 a	88.8 b
Cuprous oxide (860 g kg^-1)	120.0	33.3 b	36.5 a	40.8 a	72.5 a
Cuprous oxide (860 g kg^-1)	75.0	38.8 b	41.3 a	44.5 a	74.5 a
Cuprous oxide (860 g kg^-1)	56.3	46.6 b	49.6 b	53.3 a	87.0 b
Control		44.4 b	58.4 c	72.8 b	94.3 b
F Test		6.563 ^ significant by the analysis of variance at 1% probability of error;	8.11 ^ significant by the analysis of variance at 1% probability of error;	3.964 ^ significant by the analysis of variance at 1% probability of error;	2.92 ^* * significant by the analysis of variance at 5% probability of error.
CV (%)		8.40	6.40	12.31	39.10

Treatments	Rate	Severity
	Rate	Evaluation 1	Evaluation 2	Evaluation 3	Evaluation 4
	g 100 L^-1	08/10/2016	09/08/2016	10/06/2016	11/14/2016
1. Copper hydroxide (538 g kg^-1)	125.0	0.3 a	0.4 a	0.6 a	0.9 a
2. Copper hydroxide (538 g kg^-1)	100.0	0.4 b	0.6 b	0.8 a	1.1 a
3. Copper hydroxide (538 g kg^-1)	75.0	0.6 d	0.6 b	0.7 a	1.2 a
4. Copper oxychloride (840 g kg^-1)	200.0	0.2 a	0.4 a	0.6 a	0.9 a
5. Copper oxychloride (840 g kg^-1)	180.0	0.3 a	0.5 a	0.7 a	1.0 a
6. Copper oxychloride (840 g kg^-1)	135.0	0.4 b	0.6 b	0.8 a	1.1 a
7. Cuprous oxide (860 g kg^-1)	120.0	0.4 b	0.4 a	0.5 a	0.9 a
8. Cuprous oxide (860 g kg^-1)	75.0	0.5 c	0.5 b	0.6 a	1.0 a
9. Cuprous oxide (860 g kg^-1)	56.3	0.6 d	0.6 b	0.7 a	1.1 a
10. Control		0.7 d	0.9 c	1.1 b	1.9 b
F Test		16.21 ^ significant by the analysis of variance at 1% probability of error.	11.11 ^ significant by the analysis of variance at 1% probability of error.	4.08 ^ significant by the analysis of variance at 1% probability of error.	8.15 ^ significant by the analysis of variance at 1% probability of error.
CV (%)		4.01	3.98	6.55	6.12

Treatments	Rate	AUDPC		Orange yield
		Incidence	Disease index	Kg plant^-1
	g 100 L^-1	(%)	Disease index	11/30/2016
Copper hydroxide (538 g kg^-1)	125.0	4114.6 a	52.3 a	70.9 a
Copper hydroxide (538 g kg^-1)	100.0	5011.8 a	68.6 b	68.6 a
Copper hydroxide (538 g kg^-1)	75.0	4911.7 a	74.1 b	49.9 a
Copper oxychloride (840 g kg^-1)	200.0	4504.4 a	53.7 a	75.4 a
Copper oxychloride (840 g kg^-1)	180.0	4555.4 a	60.1 a	77.0 a
Copper oxychloride (840 g kg^-1)	135.0	5574.4 b	71.7 b	62.3 a
Cuprous oxide (860 g kg^-1)	120.0	4301.6 a	51.5 a	68.7 a
Cuprous oxide (860 g kg^-1)	75.0	4682.4 a	60.8 a	61.7 a
Cuprous oxide (860 g kg^-1)	56.3	5571.1 b	69.2 b	69.4 a
Control		6584.1 c	108.8 c	58.2 a
F Test		5.70 ^ significant by the analysis of variance at 1% probability of error; ns = not significant by the analysis of variance at 5% probability of error.	9.02 ^ significant by the analysis of variance at 1% probability of error; ns = not significant by the analysis of variance at 5% probability of error.	0.40 ns
CV (%)		6.17	7.88	39.46

Cupric fungicide	Equation model	Equation	CV (%)	F Test	R²
Copper hydroxide	Linear	$y = - 1.2523 x + 108.79$	20.69	27.178**	98.80%
Copper oxychloride	Linear	$y = - 0.5431 x + 108.82$	15.38	56.837**	99.98%
Cuprous oxide	Linear	$y = - 0.6483 x + 103.14$	14.84	60.386**	91.85%

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Brasil

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SOURCES AND CONCENTRATIONS OF CUPRIC FUNGICIDES FOR THE CONTROL OF CITRUS BLACK SPOT1

FONTES E CONCENTRAÇÕES DE FUNGICIDAS CÚPRICOS NO CONTROLE DA MANCHA PRETA DOS CITROS

ABSTRACT

SOURCES AND CONCENTRATIONS OF CUPRIC FUNGICIDES FOR THE CONTROL OF CITRUS BLACK SPOT¹