Isolation of entomopathogenic gram positive spore forming bacteria effective against coleoptera.

(1)

Irradiation of Mangoes, Irradiation of Mangoes,

Mangifera indica

Mangifera indica L. L.

Mangifera indica

Mangifera indica L. L.

N. Du Rand N. Du Rand

(2)

Introduction Introduction

South Africa mango production export drivenSouth Africa mango production export driven

India is the worlds largest producer India is the worlds largest producer

Nigeria is Africa largest producerNigeria is Africa largest producer

Mexico largest exporterMexico largest exporter

USA and EU largest importer USA and EU largest importer

Quarantine disinfestation required against:Quarantine disinfestation required against:

Mango seed weevil, Mango seed weevil, Sternochetus mangifera Sternochetus mangifera FabriciusFabricius

Mediterranean fruit fly, Mediterranean fruit fly, Ceratitis capitata Ceratitis capitata WiedemannWiedemann

Marula fruit fly, Marula fruit fly, Ceratitis cosyra Ceratitis cosyra WalkerWalker

Natal fruit fly, Natal fruit fly, Ceratitis rosa Ceratitis rosa KarschKarsch

(Asian fruit fly, (Asian fruit fly, Bacterocera papayae Bacterocera papayae Drew & Hancock)Drew & Hancock)

(3)

Deregistration of ethylene dibromide (EDB) in Deregistration of ethylene dibromide (EDB) in the USA in 1984

the USA in 1984

Search for alternative methods for phytosanitary Search for alternative methods for phytosanitary treatment of fruit and vegetables

treatment of fruit and vegetables treatment of fruit and vegetables treatment of fruit and vegetables

Various methods explored include: Various methods explored include:

Hot water Hot water

Vapour heatVapour heat

Gamma irradiationGamma irradiation

Hot water and vapour treatments not effective Hot water and vapour treatments not effective against mango seed weevil

against mango seed weevil

(4)

International accepted qurantine measures International accepted qurantine measures include:

include:

Heat treatment Heat treatment

Pest free production sitesPest free production sites Non

Non--host status host status

NonNon--host status host status

International standards for phystosanitary International standards for phystosanitary measures:

measures:

Fruit flies Fruit flies -- 250 Gy250 Gy

Seed Weevils Seed Weevils -- 300 Gy 300 Gy

(5)

Irradiation reliable quarantine disinfestation Irradiation reliable quarantine disinfestation treatment

treatment

Accepted irradiation doses results in sterility of Accepted irradiation doses results in sterility of insects

insects insects insects

Countries that irradiate and export mango Countries that irradiate and export mango include: China, India, Hawaii and Australia include: China, India, Hawaii and Australia

Mexico dominates US market Mexico dominates US market -- Feb to SeptFeb to Sept

Brazil dominates rest of the yearBrazil dominates rest of the year

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Materials and Methods Materials and Methods

Aim: Aim:

Determine the effects of irradiation on new and existing Determine the effects of irradiation on new and existing cultivars

cultivars cultivars cultivars

Cultivars:

ShellyShelly

Honey GoldHoney Gold

KeittKeitt

KentKent

(7)

Treatments:Treatments:

1. Pre1. Pre--chill, prechill, pre--cold storage and irradiationcold storage and irradiation

2. Pre2. Pre--chill, irradiation and postchill, irradiation and post--cold storagecold storage

3. No pre3. No pre--chill, irradiation and postchill, irradiation and post--cold storagecold storage

Logistics:Logistics:

Monday Monday –– Fruit picked and standard pack house treatment Not for Fruit picked and standard pack house treatment Not for treatment 3)

treatment 3)

Wednesday Wednesday -- Transported to Pietermaritzburg at 10Transported to Pietermaritzburg at 10⁰⁰C air temperatureC air temperature

Thursday Thursday –– Fruit collected from market, weighed and stored at 9Fruit collected from market, weighed and stored at 9⁰⁰C C

Saturday Saturday –– Fruit irradiated Gamwave SA (Pty) Limited in DurbanFruit irradiated Gamwave SA (Pty) Limited in Durban

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Doses: 300, 400, 600 and 1000 GyDoses: 300, 400, 600 and 1000 Gy

Stack of five cartons per dose Stack of five cartons per dose

Stack was turned 180Stack was turned 180Stack was turned 180Stack was turned 180 at half time⁰⁰ at half timeat half timeat half time

Irradiation time influenced by product Irradiation time influenced by product

(9)

Figure 1. Cartons stacked on trolleys facing the gamma radiation source.Figure 1. Cartons stacked on trolleys facing the gamma radiation source.

(10)

Figure 2. Gamma radiation source submerged in water.Figure 2. Gamma radiation source submerged in water.

(11)

Dosimetery:Dosimetery:

Harwell Amber Perspex Dosimeter (Type 3042) Range 1Harwell Amber Perspex Dosimeter (Type 3042) Range 1-- 30kGy

30kGy

Dosimeters preDosimeters pre--dosed for 1.5dosed for 1.5--2 hrs2 hrs

Reading were taken with spectrometer and dose calculatedReading were taken with spectrometer and dose calculated

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Fruit evaluation:Fruit evaluation:

Blush 0 Blush 0 –– 3 ( 0 = no blush)3 ( 0 = no blush)

Skin colouration 0 Skin colouration 0 -- 3 (0 = no colouration)3 (0 = no colouration)

Cold damage 0 Cold damage 0 –– 3 (0 = no damage)3 (0 = no damage)

Firmness Firmness -- densimeterdensimeter

Lenticel damage (0 = no damage)Lenticel damage (0 = no damage)

Moisture lossMoisture loss

Days to ripeDays to ripe

Soft brown rot 0 Soft brown rot 0 –– 3 (0 = no rot)3 (0 = no rot)

Anthracnose 0 Anthracnose 0 –– 3 (0 = no anthracnose)3 (0 = no anthracnose)

Vascular browningVascular browning

Internal colourInternal colour

TSS (Brix)TSS (Brix)

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Results and Discussion Results and Discussion

Cultivar Aimed dose

(Gy)

Dose for Treatment

1 (Gy)

Dose for Treatment

2 (Gy)

Dose for Treatment

3 (Gy)

Honey Gold and Shelly 300 260 366 366

400 470 460 460

600 710 590 590

1000 1000 970 970

Keitt and Kent 300 290 310 310

400 363 370 370

600 680 646 646

1000 1020 1035 1035

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Lenticel damage Lenticel damage

80 100

Honey Gold lenticel damage for Treament 1

0 20 40 Percentage 60

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(15)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(16)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(17)

80 100

Shelly lenticel damage for Treament 1

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(18)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(19)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(20)

80 100

Keitt lenticel damage for Treament 1

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(21)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(22)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3 0

(23)

80 100

Kent lenticel damage Treatment 1

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(24)

80 100

Kent lenticel damage for Treatment 2

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(25)

80 100

Kent lenticel damage for Treatment 3

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(26)

Cold damage Cold damage

80 100

Honey Gold cold damage for Treatment 1

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(27)

80 100

Honey Gold Cold damage for Treatment 2

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(28)

80 100

Honey Gold cold damage for Treatment 3

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(29)

80 100

Shelly cold damage for Treatment 1

fruit damaged

0 300 400 600 1000

Dose (Grays)

0 1 2 3

(30)

80 100

Shelly Cold damage for Treatment 2

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(31)

80 100

Shelly cold damage for Treatment 3

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(32)

80 100

Keitt cold damage for Treatment 1

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(33)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(34)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(35)

80 100

Kent cold damage for Treatment 1

fruit damaged

0 300 400 600 1000

dose (Gray)

0 1 2 3

(36)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

(37)

80 100

fruit damaged

0 300 400 600 1000

Dose (Gray)

0 1 2 3

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(39)

(40)

(41)

(42)

(43)

(44)

(45)

(46)

(47)

(48)

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TSS TSS

17.5 18

Honey Gold Total soluble solids (TSS) for all three treatments

15 15.5 16 16.5 17 17.5

Total soluble solids

0 300 400 600 1000

Dose (Gray)

Treatment 1 Treatment 2 Treatment 3

(51)

18 18.5

Shelly total soluble solids (TSS) for all three treatments

16 16.5 17 17.5 18 Total soluble

solids

0 300 400 600 1000

Dose (Gray)

(52)

15.5 16

Keitt total soluble solids (TSS) for all three treatments

12.5 13 13.5 14 14.5 15 15.5

Total soluble solids

0 300 400 600 1000

Dose (Gray)

(53)

17 18

Kent total soluble solids (TSS) for all three treatments

13 14 15 16 17 Total soluble

solids

0 300 400 600 1000

Dose (Gray)

(54)

Percentage moisture loss:Percentage moisture loss:

Honey Gold 5Honey Gold 5--7%7%

Shelly 10Shelly 10--12%12%

Keitt 10Keitt 10--12%12%

Kent 8Kent 8--10%10%

No difference in taste No difference in taste

(55)

Problems Problems

Stem end rot and soft brown rot caused major Stem end rot and soft brown rot caused major losses

losses

Requires higher doses of Gamma radiation to Requires higher doses of Gamma radiation to control fungi

control fungi -- 1300 Gy1300 Gy control fungi

control fungi -- 1300 Gy1300 Gy

(56)

Stem end rot Stem end rot

(57)

Stem end rot on Shelly Stem end rot on Shelly

(58)

(59)

(60)

Conclusion Conclusion

Post harvest diseases are a huge problemPost harvest diseases are a huge problem

Cold damage does increase with increasing doseCold damage does increase with increasing dose

Lenticel damage increases with doseLenticel damage increases with dose There is no large difference in:

There is no large difference in:

There is no large difference in:There is no large difference in:

TasteTaste

Moisture lossMoisture loss

(61)

Acknowledgements Acknowledgements

Westfalia/Bavaria FundingWestfalia/Bavaria Funding

WTS: Fruit Therese Bruwer and Zelda van WTS: Fruit Therese Bruwer and Zelda van Rooyen

Rooyen

GAMWAVE: Ron Lunt and Graham LuntGAMWAVE: Ron Lunt and Graham Lunt

GAMWAVE: Ron Lunt and Graham LuntGAMWAVE: Ron Lunt and Graham Lunt Thank you

Thank you