A Spray Program for the Control of Black Sigatoka
ChavarrĂa-Carvajal, J.A., R. Macchiavelli, and E. HernĂĄndez.
Introduction: n
Bananas (Musa acuminata, AAA) and plantains (Musa acuminata X M. balbisiana, AAB) are two of the most important tropical fruits.
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During fiscal year 2009-10 the combined farm gate value of bananas and plantains reached $78.7 million. Plantains rank first in economic importance with a farm gate value of $69.1 million, representing 8.76 % of the local gross agricultural income; while bananas for the same period had a farm gate value of $9.6 million or 1.2 % of the local gross agricultural income.
§ Bananas and plantains have several natural enemies including bacteria, viruses, insects, nematodes, and fungi.
§
Among the fungi, two related Ascomycetes are most significant: Mycosphaerella fijiensis (anamorph Pseudocercospora fijiensis), cause of black Sigatoka (BS), and M. musicola (anamorph Pseudocercospora musae), cause of yellow Sigatoka (YS) (Carlier et al., 2000).
§ During summer of 2004, BS was found on several plantain and banana farms in Puerto Rico on the western side of the Island and later (2006) was confirmed (Irish et al., 2006).
n
Since then BS has replaced the common YS, contributing to severe yield reductions on banana and plantain production.
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BS is more aggressive and destructive than YS. Without proper management practices BS can cause losses in banana of 50% or higher (Stover, 1983), and losses in plantain of more than 40% (Chavarría-Carvajal 1986).
n
To produce commercially acceptable banana fruit, it is necessary to use fungicides intensively. Although YS management may require as many as 15 spray applications per year, up to 45 are used to manage BS. Thus, BS management is 3 to 4 times more expensive than YS.
Objectives: 1. To develop an effective spray program for the control of BS based on local weather conditions and available chemicals. 2. To evaluate the effects of spray program on BS severity index and yield parameters.
Materials and Methods
Isabela n
n n n n
Experimental site: located northwest of Puerto Rico An elevation of 15.0 meters above sea level Average annual rainfall 1,630 mm Average temperature 24.0 ° C. Predominant soil series is a Coto (Very-fine, kaolinitic, Typic isohyperthermic Eutrustox soil "), with pH of 6.2
Corozal § Experimental site: located northern Puerto Rico § An elevation of 209.1 meters above sea level § Average annual rainfall 2,500 mm § Average temperature 24.8 ° C. § Predominant soil series is a Corozal clay (clayed, mixed isohyperthemic aquic tropudult), with pH of 5.0
Experimental Design: Split Plot 6 replicates and 2 treatments. Banana (Musa acuminata, AAA cv. ‘Grand Naine�) Experimental Plot: 4 Rows- 10 plants each Plants studied: 2 rows- 5 plants each Spaced: 2.4 m rows X 2.1 m plants Population Density: 1,983 plants/hectare
Fungicides 1. Tilt (propiconazole): systemic, single-site fungicide, DMIsterol biosynthesis inhibitor. 2. Abound (azoxystrobin): systemic, single site fungicide, strobilurin or QoI-respiration inhibitor. Tilt & Abound were used only during the rainy season or in periods of high inoculum pressure. Not more than two consecutive blocks. Not more of six cycles per year, per crop cycle to avoid the development of resistant strains.
3. Bravo WS (chlorothalonil): wide-spectrum, non-systemic, oil-incompatible, inhibits development young pathogen lesions on leaf surface. Applied during periods with medium inoculum pressure or when rainy season was not severe. 4. Manzate (mancozeb): protectant fungicide. Applied in periods with low inoculum pressure or during dry season.
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Propiconazole (Tilt), azoxystrobin (Abound), and macozeb (Manzate) applied in a oil-water emulsion. Chlorothalonil (Bravo WS) applied in water.
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Fungicide applications from ground level with a motorized backpack sprayer calibrated to deliver a total volume of 34 to 45 L/acre (85-112 L/ha).
Severity Index % (S.I)1 Logarithmic, categorical scale (7 disease categories) Visual estimate for each leaf Based on the International rating system for BS Leaves numbered from top to down-wards Grade 0
Grade 1 (< 1%)
Grade 2 (1-5 %)
Grade 3 (6-15%) Grade 4 (16-33%) Grade 5 ( 34-50%) Grade 6 (> 51%)
1 Gauhlâ&#x20AC;&#x2122;s
modification of Stoverâ&#x20AC;&#x2122;s severity scoring system.
Severity Index % (S.I) Where:
ÎŁnb x 100 (N-1) T
n = number of leaves in each grade b = grade (0 = symptomless, 1 = less than 1% of leaf area affected (only streaks and/ or up to 10 spots), 2 = 1-5% of leaf area affected, 3 = 6-15% of leaf area affected, 4 = 16-33% of leaf area affected, 5 = 34-50% of leaf area affected, and 6 = 51-100% of leaf area affected. N = total number of grades in the scale (7) T = total number of leaves assessed. Craenen (1998)
RESULTS
Banana Plant Crop
Table 1. Spray Program for the control of BS on the banana plant crop at Isabela1
Fungicide
Date
Bravo WS
July 7, 2010
Cocktail Manzate
August 10, 2010
Bravo WS
August 25, 2010
Cocktail Tilt
September 8, 2010
Cocktail Tilt
September 29, 2010
Cocktail Abound
October 13, 2010
Cocktail Abound
October 21, 2010
Bravo WS
November 17, 2010
Bravo WS
December 15, 2010
Cocktail Tilt
January 4, 2011
1 Fungicides
Total: 10 spray cycles Cocktail Tilt (propiconazole): Cocktail Abound (azoxystrobin): Cocktail Manzate (mancozeb): Bravo WS (chlorothalonil):
3 2 1 4 10
(Tilt, Abound and Manzate) were sprayed in an oil-water emulsion, meanwhile Bravo WS in a water-emulsion, based on manufacturer recommendations. Orchard Oil BVA#15 based on manufacturer recommendations.
Table 2. Spray Program for the control of BS on the banana plant crop at Corozal1 Fungicide
Date
Cocktail Tilt
June 18, 2010
Cocktail Tilt
July 07, 2010
Cocktail Abound
July 22, 2010
Cocktail Abound
August 06, 2010
Bravo WS
August 23, 2010
Cocktail Tilt
September 10, 2010
Cocktail Tilt
September 24, 2010
Cocktail Abound
October 07, 2010
Cocktail Abound
October 22, 2010
Bravo WS
November 05, 2010
Bravo WS
November 26, 2010
1 Fungicides
Total: 11 spray cycles Cocktail Tilt (propiconazole): 4 Cocktail Abound (azoxystrobin): 4 Bravo WS (chlorothalonil): 3 11
(Tilt, Abound and Manzate) were sprayed in an oil-water emulsion, meanwhile Bravo WS in a water-emulsion, based on manufacturer recommendations. Orchard Oil BVA#15 based on manufacturer recommendations.
Table 3. BS severity index on banana plant crops at Isabela and Corozal Isabela: Chemical
SI (%)
SI (%)
Flowering
Harvesting
None
47.88 A
100.00 A
Yes
35.90 B
83.72 B
Chemical
SI (%)
SI (%)
Flowering
Harvesting
None
69.88 A
98.59 A
Yes
66.89 A
98.01 A
Corozal:
Table 4. Effects of spray program on yield parameters for the banana plant crops at Isabela and Corozal1,2,3 Isabela: Bunch weight -54.6% yield reduction. Chemical
Fruits/bunch Hands/bunch
Fruits 1rst Hand
Fruits 2nd Hand
Bunch Weight (Kg)
Mean Fruit Weight (g)
None
118.89 A
7.80 B
19.30 A
16.96 A
11.21 B
94.75 B
Yes
125.30 A
8.30 A
19.36 A
17.47 A
24.72 A
198.55 A
Corozal: Bunch weight -53.8% yield reduction. Chemical
Fruits/bunch Hands/bunch
Fruits 1rst Hand
Fruits 2nd Hand
Bunch Weight (Kg)
Mean Fruit Weight (g)
None
136.69 A
8.50 A
21.47 A
17.97 A
11.13 B
82.53 B
Yes
142.24 A
8.67 A
21.76 A
19.40 A
23.07 A
163.66 A
LS-means with the same letter are not significantly different at Îą â&#x2030;¤ 0.05 3 Bunch weight without rachis. 1
2 Average
of 6 replicates
First Banana Ratoon
Table 5. Spray Program for the control of BS on the first banana ratoon at Isabela1
Fungicide
Date
Cocktail Abound
May 26, 2011
Cocktail Abound
June 8, 2011
Cocktail Tilt
June 30, 2011
Cocktail Tilt
13 July, 2011
Cocktail Manzate
August 10, 2011
Cocktail Manzate
August 25, 2011
Cocktail Manzate
September 7, 2011
Bravo WS
September 27, 2010
Cocktail Abound
October 19, 2011
Cocktail Abound
November 3, 2011
Bravo WS
November 17, 2011
1 Fungicides
Total: 11 spray cycles Cocktail Tilt (propiconazole): Cocktail Abound (azoxystrobin): Cocktail Manzate (mancozeb): Bravo WS (chlorothalonil):
2 4 3 2 11
(Tilt, Abound and Manzate) were sprayed in an oil-water emulsion, meanwhile Bravo WS in a water-emulsion, based on manufacturer recommendations. Orchard Oil BVA#15 based on manufacturer recommendations.
Table 6. Spray Program for the control of BS on the first banana ratoon at Corozal1 Fungicide
Date
Fungicide
Date
Cocktail Abound
February 15, 2011
Cocktail Tilt
July 28, 2011
Cocktail Abound
March 1, 2011
Cocktail Tilt
August 12, 2011
Bravo WS
March 16, 2011
Cocktail Abound
August 25, 2011
Bravo WS
March 31, 2011
Cocktail Abound
September 12, 2011
Bravo WS
April 20, 2011
Bravo WS
September 29, 2011
Bravo WS
May 10, 2011
Bravo WS
October 14, 2011
Cocktail Abound
May 25, 2011
Bravo WS
October 29, 2011
Cocktail Abound
June 10, 2011
Cocktail Tilt
November 14, 2011
Bravo WS
June 24, 2011
Cocktail Tilt
November 28, 2011
Bravo WS
July 12, 2011
1 Fungicides
Total: 19 spray cycles Cocktail Abound (azoxystrobin): 6 Cocktail Tilt (propiconazole): 4 Bravo WS (chlorothalonil): 9
(Tilt, Abound and Manzate) were sprayed in an oil-water emulsion, meanwhile Bravo WS in a water-emulsion, based on manufacturer recommendations. Orchard Oil BVA#15 based on manufacturer recommendations.
19
Table 7. BS severity index on banana first ratoon at Isabela and Corozal Isabela: Chemical
SI (%) Flowering
None
41.04 A
Yes
39.97 A
Chemical
SI (%)
Corozal: Flowering None
55.81 A
Yes
48.65 A
Table 8. Effects of spray program on yield parameters of the first banana ratoon at Isabela and Corozal1,2,3 Isabela: Bunch weight -45.6% yield reduction. Chemical
Fruits/bunch Hands/bunch
Fruits 1rst Hand
Fruits 2nd Hand
Bunch Weight (Kg)
Mean Fruit Weight (g)
None
118.46 B
7.93 A
18.57 B
17.29 A
13.85 B
116.76 B
Yes
144.21 A
8.93 A
21.41 A
18.55 A
25.46 A
176.16 A
Corozal: Bunch weight -33.2% yield reduction. Chemical
Fruits/bunch Hands/bunch
Fruits 1rst Hand
Fruits 2nd Hand
Bunch Weight (Kg)
Mean Fruit Weight (g)
None
104.41 A
7.52 A
17.75 A
14.93 A
11.30 B
108.23 B
Yes
116.41 A
8.02 A
19.84 A
16.44 A
24.35 A
209.17 A
LS-means with the same letter are not significantly different at Îą â&#x2030;¤ 0.05 3 Bunch weight without rachis. 1
2 Average
of 6 replicates
Chemical Control
None Chemical Control
Conclusions:
§ Spray Program improved crop yield on bananas. § Chemical control: intensive and expensive. § Corozal: due to high inoculum pressure and persistant rainy period the use of protectant fungicides (e.g. mancozeb - not possible).
§
BS severity: Isabela: PC -54.6%, RC -45.6% yield reduction. Corozal: PC: -53.8%, RC -33.2% yield reduction
Acknowledgment Dr. Raúl Macchiavelli Mr. Evelio Hernández Mr. Armindo Santiago. Mr. Angel Cabán (Layo) Mr. Efraín Cancel Field Personnel at Corozal & Isabela Stations Program FIDTA: PRACTICES FOR THE CONTROL OF Black Sigatoka IN PUERTO RICO
Questions?