Twin pest risks for fei­joas

Grow­ers get the low-down from sci­en­tists.

The Orchardist - - Feijoas - By Wendy Lau­ren­son

Around 5L fei­joa grow­ers from around the coun­try met in gerik­eri in mid-jovem­berH for their an­nual meet­ingH two fei­joa or­chard field vis­its, and pre­sen­ta­tions from Auck­land-based llant B bood sci­en­tists on an­thrac­nose and guava mothJ

At the meet­ingH long serv­ing pres­i­dentH brans de fongH stepped down and Roger iatthew was elected to the roleJ

With both guava moth and an­thrac­nose be­com­ing se­ri­ous is­sues for North­land fei­joa grow­ers, the field days were a chance for grow­ers from other re­gions to see first-hand some of the chal­lenges they’re fac­ingH and what pre­ven­ta­tive steps may mit­i­gate dam­ageJ The meet­ing recog­nised the im­por­tance of these chal­lenges by agree­ing to make the fund­ing for pro­duc­tion is­sues and re­search a pri­or­ity over pro­mo­tionJ

Vis­its to two gerik­eri fei­joa or­chards brought the area’s mas­sive pro­duc­tion loss into stark re­al­i­tyJ Ian TurkH jZ bei­joa Grow­ers As­so­ci­a­tion man­agerH said gerik­eri’s fei­joa pro­duc­tion has gone from about 2LL tonnes five years ago to 10M5 tonnes last sea­sonH and that loss was pri­mar­ily due to an­thrac­noseJ

“This species of ag­gres­sive an­thrac­nose is par­tic­u­larly vir­ile and unique in that it at­tacks im­ma­ture fruit in trees, and it’s prov­ing dif­fi­cult to man­ageH” he saidJ “The ex­tent of the im­pact and its rapid spread up here is putting us all on alertJ It’s some­thing we have to make a pri­or­i­tyJ”

kn leter and Deb­bie fack’s or­chardH vis­i­tors saw how they had been bat­tling with guava moth for years but in re­cent sea­sons ag­gres­sive an­thrac­nose has been their ma­jor is­sueJ

“We’ve taken a third of our trees out and this year we didn’t send any fruit to our mar­ket­ing com­pany be­cause of our con­cerns of spreading the dis­easeH” leter saidJ “Ini­tially you can’t see it but it can show up on fruit a few days lat­erJWe still have 5LL fei­joa trees and some of those are young re­plants that showed ev­i­dence of in­fec­tion and dieback be­fore they were ma­ture enough to even fruitJ jorth­land is par­tic­u­larly sus­cep­ti­ble to spread of ag­gres­sive an­thrac­nose be­cause of our warm wet cli­mate and un­til this year grow­ers from other re­gions haven’t taken it se­ri­ous­lyJ We’re now all re­al­is­ing that the spread of it can be just a puff of wind awayJ”

Other Kerik­eri field day hosts, Ian and Tracy, first no­ticed an­thrac­nose on one tree in their or­chard in 2LM5J

“We had it in OL trees by 2LMRH 2LL trees in 2LM7H and MRLL trees in 2LMTH” Ian saidJ

“Tracy and I ini­tially had MTLL trees and we took MOLL outH leav­ing us with just 5LL treesJ We can’t af­ford the eco­nomic risk of pre­par­ing a crop and hir­ing labour only to lose a big pro­por­tion of itH so we left in just enough trees for us to be able to han­dle our­selvesJ”

Dr lia Rhein­län­derH a sci­en­tist from llant B bood in Auck­land work­ing with an­thrac­noseH pre­sented the lat­est in­for­ma­tion to grow­ers at the gerik­eri llant B bood Re­search Sta­tionJ She said ag­gres­sive An­thrac­nose in fei­joas caused sig­nif­i­cant fruit drop and was re­ported in MM or­chards in gerik­eri in 2LMT with es­ti­mated crop losses of up to TL per­centJ Two sim­i­lar cases were first re­ported and con­firmed by the Min­istry for Pri­mary In­dus­tries DilIE on gerik­eri or­chards in 2LL5 and 2LMMJ

The fun­gus caus­ing this par­tic­u­larly ag­gres­sive an­thrac­nose DCol­letotrichum theo­bromi­co­laEH is dif­fer­ent from ei­ther Col­letotrichum acu­ta­tum or Col­letorichum gloeospo­ri­oides which also cause an­thrac­nose in fei­joas but don’t cause pre­ma­ture fruit drop and are typ­i­cally only seen posthar­vest or on ripe fruitJ

“The dis­ease ap­pears to be spreading from or­chard to or­chard by mi­cro­scopic spores car­ried by rain and windH” she saidJ

“It’s very ag­gres­sive and cur­rent fungi­cide treat­ment pro­grammes have had lit­tle or no ef­fectJ There are so far no re­ports out­side jorth­land but there is con­cern that the dis­ease could spread to other re­gions which could be dev­as­tat­ing for the jZ fei­joa in­dus­tryJThe ur­gent need for a control pro­gramme has re­sulted in a Sus­tain­able barm­ing bund DSbbE ap­pli­ca­tion be­ing sub­mit­ted in Au­gust 2LMTJ”

The ag­gres­sive an­thrac­nose first shows up as pur­plish sunken spots on the fruit about a month be­fore ripen­ingH then these en­large to de­velop cen­tres cov­ered in slimy sal­mon-coloured spore mass­esJ In­fec­tion of the fruit causes them to drop pre­ma­turely and there is some ev­i­dence that this an­thrac­nose can also cause dieback of branch­esJ

The dis­ease doesn’t spread through the vas­cu­lar sys­tem of the plant but rather pro­lif­er­ates through mul­ti­ple in­fec­tion sitesJ

“The spores ger­mi­nate on the plant sur­face and pro­duce an in­fec­tion peg that in­fects the plant tis­sue where it can re­main la­tent for a long pe­ri­odH” she saidJ “In­fec­tion of fruit can oc­cur at any time be­tween flow­er­ing and fruit ripen­ing but the symp­toms don’t ap­pear un­til about a month be­fore fruit ma­tu­ri­tyJ”

“We’re not yet sure of the dis­ease cy­cle but pre­sume it’s sim­i­lar to the way an­thrac­nose be­haves in other hor­ti­cul­tural crop­sJThis cy­cle goes from fruit tree canopy to pre­ma­ture fruit dropH to over­win­ter­ing in fruit mum­miesH dead branches and leavesJ iicro­scopic spores are then dis­persed back through the canopy and this re­sults in re­peat cy­cles of in­fec­tionJ ”

Con­trol­ling the dis­ease would re­quire a com­bi­na­tion of three strate­giesJ

“We may find that some ex­ist­ing fei­joa cul­ti­vars are more tol­er­ant of the fun­gusH and re­search is be­ing planned to screen the sus­cep­ti­bil­ity to the dis­ease of com­mer­cial cul­ti­varsJ”

This would take some time to find out but a pro­tec­tive fungi­cide pro­gramme could pre­vent in­fec­tionJ

“So we are also hop­ing to un­der­take lab­o­ra­tory and field test­ing of fungi­cides to de­velop a chem­i­cal spray pro­gramme which will al­low grow­ers to man­age the dis­ease and de­liver residue-free fruit.This work will in­volve sig­nif­i­cant par­tic­i­pa­tion of grow­ersJ”

kr­chard cul­tural and hy­giene prac­tices of re­mov­ing over­win­ter­ing and re­in­fec­tion sources would help erad­i­cate in­ocu­lumJ All were ar­eas which would be re­searched un­der the SSb pro­jectH with a de­ci­sion on the ap­pli­ca­tion ex­pected soonJ

Ian aid most fei­joa grow­ers wanted to be sure they were in­formed in or­der to pro­tect our liveli­hoods and our in­dus­tryJ

“Al­though the vol­umes of pro­duc­tion have dropped na­tion­wideH there is still good in­ter­est in ex­port­ingH the do­mes­tic de­mand is buoy­antH and there is now a strong pro­cess­ing base of juice and pureeH” he saidJ

“kur in­dus­try may be small but it’s a key con­trib­u­tor in some re­gions and it’s vi­tally im­por­tant we main­tain best prac­tices to take care of itJ”

“We’re now all re­al­is­ing that the spread of it can be just a puff of wind away.”

Newspapers in English

Newspapers from New Zealand

© PressReader. All rights reserved.