Reasons for inconsistent control of citrus canker

Transcription

1 Reasons for inonsistent ontrol of itrus anker Jim Graham Citrus Institute April 7, 2015 Avon Park

2 Canker Bateria Dissemination

3 Copper film annot protet entry points when the rain droplets exeed 18 mph Copper film Continuous water olumn forms Substomatal hamber flooding

4 Stomatal infetions of grapefruit leaves and fruit

5 Site onditions that promote anker are wide open areas without natural windbreaks

6 Canker ontrol and resultant fruit drop in Hamlin oranges is diffiult to manage due to wind exposure

7 Effet of windbreaks on wind speed and anker inidene on grapefruit 2014 Previous researh has shown that wind speed influenes infetion with X, and wind breaks may help redue disease Wind speeds >18 mph inrease infetion of sweet oranges by X Objetive: Charaterize wind speed and anker severity at different loations in bloks surrounded by Corymbia torelliana windbreaks (6-10 m tall) Trials at two east oast grapefruit groves: Indian River Co., St. Luie Co.

8 Effet of windbreaks on anker severity on grapefruit - ollaboration with Clive Bok USDA-ARS Foliage assessment sale: 0 = 0% leaves with any anker 1 = 1-15 % leaves with any anker 2 = % leaves with any anker 3 = % leaves with any anker 4 = % leaves with any anker 5 = % leaves with any anker On fruit perent area ankered estimated and number of lesions ounted

9 Canker severity on fruit (number of lesions) Canker severity on fruit (number of lesions) Effet of distane from the windbreak on severity of anker on grapefruit Linear relationship between anker severity (no. of lesions/fruit) and distane from the windbreak Results onfirm that the loser itrus trees are to windbreaks, the lower the inidene and severity of anker on fruit Estes grove Sott grove y = x R² = y = x R² = Distane from the wind break (ft) Disease assessed Otober 2014 Distane from the windbreak (ft)

10 Promoting vigor in young trees: more suseptible to itrus leafminer (CLM) and fruit infetion More flushes per tree anopy volume our on younger fruiting trees Repeated vigorous and offyle flushes are highly vulnerable to CLM Infetion of suseptible, wounded tissue promotes explosive inrease in leaf inoulum Rapid build-up on leaves puts the developing fruit at risk for infetion Leaf miner ontrol is essential for anker ontrol on younger trees

11 Contat with opper an ontrol bateria that exude from CLM-indued infetions Bateria in mine

12 Cu sprays at 21 day interval protet fruit from 0.25 to 1.5-inh diameter: spray gallonage, trator speed for overage of fruit

13 Cu residue on fruit is depleted by 21 days due to fruit growth; unaffeted by rainfall (Cu film is stable!) 1.8 Fruit Cu residue ( g/surfae area) High rainfall period Low rainfall period Days after appliation

14 Hamlin with severe early season fruit infetion and drop ue to a missed opper spray and rain events in April-May 2011 (50% rop loss) Valenias in same grove with no anker-indued drop Hamlins

15 Early season anker indued fruit drop is due to April-May rains, not inoulum arry over from previous season Fruit dropped/tree due to anker Rainfall (inhes) Sebring Rainfall April-May 2011 Total rainfall 15 min max 0 Cu treated Untreated Cu treated Untreated 0.0 Apr 1 Apr 15 May 1 May 15 May 31 Treatment Date

16 Formulations, rates of produts for Ray grapefruit in 2013 Treatment Manufaturer /supplier Copper formulation Metalli Cu (%) Rate of Produt (1b/a) Koide 2000 Dupont hydroxide Koide 3000 Dupont hydroxide Nordox 75WG 1.33 Nordox oxide Nordox 75WG 1.0 Nordox oxide Champ 30WDG Nufarm hydroxide Regalia (biologially Marrone based) Untreated hek (UTC) Metalli Cu (lb/a)

17 Cu formulations are equally effetive at 21 day interval; biofungiide is less effetive and more expensive Fruit anker inidene (%) d d d Canker d b a Melanose inidene (%) Melanose - Diaporthe itri Koide lb/a Koide lb/a Nordox 75G 1.33 lb/a b Nordox 75G 1.0 lb/a Champ 30 WDG 3.0 lb/a Sab - Elsinoe fawetii Regalia a UTC a 0 Koide lb/a Koide lb/a Nordox 75G 1.33 lb/a Nordox 75G 1.0 lb/a Champ 30 WDG 3.0 lb/a Regalia UTC Sab inidene (%) Koide lb/a Koide lb/a Nordox 75G 1.33 lb/a Nordox 75G 1.0 lb/a Champ 30 WDG 3.0 lb/a b Regalia UTC

18 Cu sprays redue rop loss about 50% Return on spray ost drops as trees form hedgerows $365 without opper with opper Fruit Drop (Boxes/tree) $50 $ Year

19 Interation with HLB and its management HLB greatly disrupts yles of flowering, fruit set and foliar flushing Canker is either suppressed or exaerbated depending on the inoulum present and hortiultural management This past season, young trees were markedly redued in foliar flush yles in onjuntion with a low number of signifiant rainfall events in April-May Inoulum failed to build up as expeted based on experiene prior to the prevalene of HLB

20 Enhanement of anker by foliar nutrition programs Grapefruit and Hamlins managed with an aggressive foliar nutritional program onstantly flushed oinident with periodi rains These anker-onduive onditions rendered a welltimed, 21-day opper sprays almost ompletely ineffetive

21 Aknowledgements CREC Labs: Monty Myers Diane Bright Tony MIntosh Alex Dunn Kayla Gerberih Grove study ooperators: Sott Citrus Estes Citrus Crews Citrus Funding: KAC Agriultural In: Henry Yone Carol Brooks