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IPDM withstands pests, diseases and natural disasters


Training day Yarra Valley (Image taken prior to physical distancing requirements).

This article was written by David Williams and Emily Crawford for the Spring edition of Australian Frutigrower Magazine.

Growers looking to solve pest and disease issues or improve management with less recourse to chemicals now have a raft of tools, regional case studies and practical expert advice at their disposal on the new apple and pear integrated pest and disease management (IPDM) website.

Set up in 2018 by Agriculture Victoria and funded by Hort Innovation using the apple and pear industry levy, the Australian Apple and Pear IPDM site  aims to provide industry with the resources needed to build more pest-resilient systems and has already attracted thousands of visits.

The interactive online hub and allied Facebook group offer timely advice and information on emerging seasonal issues, updated resources and also gives growers the opportunity to ask advice of a national team of panel of experts, discuss approaches and share their own experiences.

Regular updates from case study orchards in each region give practical insights into how growers are using IPDM to tackle common pest and disease issues in the orchards and how it is working.

In addition, the webpage hosts the revised Apple and Pear IPDM Manual, numerous IPDM monitoring templates and videos to assist growers establish an IPDM system, and reports on IPDM case studies. The popular Pocket Guide to Pests of Pome and Stone fruit and their Predators and Parasitoids has been digitised, has interactive features, and is available for free download on the IPDM webpage.

The webpage has already attracted strong interest with over 5,957 users and 15,059 pageviews. The Facebook group, open only to Australian growers and advisors, now has over 100 members.

IPDM training sessions and orchard walks have been held in each state and case study orchards have demonstrated how growers are implementing IPDM – documenting what works and what hasn’t worked. Eight case study orchards participated in the 2019–20 season to address challenges identified in their IPDM Action Plans.

Tried and tested

Queensland: Mites and mealybugs had become major problems in recent years for Daniel Nicoletti, at Stanthorpe, possibly as a side effect of the previous insecticide program for mealybug impacting on predatory mites and ladybird beetles. Daniel started the season with the orchard suffering from the effects of long-term drought and facing the driest year on record. The hot dry weather continued with 33 days of maximum temperatures over 30 degrees in December and January, but rain eventually arrived with heavy falls in mid-January through to mid-February. Daniel has one of the local agronomists do his pest monitoring and only one of the seven monitored blocks had codling moth recorded in traps. Damage recorded at harvest for that block from codling moth was 2 per cent and 4.2 per cent from mealybug, a reasonable result given the carryover pest pressure from the previous season and the weather conditions in 2019–20. The mite population monitoring results provided by Daniel’s agronomist as per cent leaves infested have been converted to cumulative leaf infested days (CLIDs) for presentation because damage by mites is a product of per cent leaves infested and the number of days they are infested. The CLIDs graph (Figure 1) suggests that there may be a problem developing in block 1 where the miticide applications had little effect on the slope of the curve.

Figure 1: Cumulative Leaf Infested Days for four blocks in the Nicoletti case study 2019-20

CLIDs was first developed for use in Williams Bon Chrétien (WBC) pears which are highly sensitive to mite damage. Since then we have also used CLIDs in Packham pears and in apples. The thresholds we use are 1500 CLIDs for WBC; 3000 CLIDs for Packhams; and >50000 CLIDs for apples. These thresholds are the maximum for the season, rather than for instantaneous readings, and the cumulative presentation of the results allows the grower to read the slope and estimate how quickly the threshold will be reached if no intervention is applied. In Daniel’s case he was able to keep even his worst block below the threshold of 5000 CLIDs and should not see any reduction in yield due to mite feeding.

NSW: Woolly apple aphid (WAA) was the major focus of Batlow grower Jeremy Smart, followed by codling moth and apple scab. Jeremy used mating disruption backed up with Altacor for his codling moth control and spot spraying against WAA where the parasitoid wasp Aphelinus mali or predation by earwigs was insufficient to prevent localised outbreaks. Jeremy installed a local weather station and used RIMpro software to help time his codling moth and apple scab sprays. The Rosy Glow block recorded 0.4 per cent codling moth damage and the Fiero Fuji block had no codling moth damage. WAA populations at the harvest assessment date were heavily parasitised (70 per cent) by A.mali and mite populations were under control with only 10 per cent leaves infested and predatory mites found on 50 per cent of leaves. Unfortunately, the orchard was affected by the Batlow bush fires.

Victoria: In the Yarra Valley David Finger’s main concern was codling moth and apple scab in the netted Granny Smith block used for the case study, and mites were becoming an issue. David used RIMpro software to guide his codling moth and apple scab control. Aphelinus mali was present in good numbers. Earwigs present in good numbers were probably contributing to WAA and codling moth control. Predatory mites had been released to control two-spotted mites, European red mites, and Bryobia. David maintains a weed free tree line, root prunes to control vigour, and does not worry too much about the inter-row although he uses a narrow mulching mower that leaves a few weeds on the edge to support predators. He used no insecticides in the case study block and damage was below economic thresholds with only 1.4 per cent damage by apple dimpling bug, 0.4 per cent damage by codling moth, 0.4 per cent damage from light brown apple moth, 0.6 per cent damage from apple scab and no evident mite damage.

Tasmania: John Evans considered the pests and diseases in his Geeveston orchard were under control, despite some edge issues with codling moth, and he used a minimal spray program. Earwigs and A. mali were present and controlling WAA despite a spring application of chlorpyrifos against the Tasmanian dimple bug. He experimented with the codling moth line trapping concept, introduced by visiting scientist Chris Adams from Michigan State University in the 2018–19 training workshops, to identify appropriate timing of codling moth sprays and avoided the edge effects experienced in the previous season. Damage recorded at harvest in the case study Fuji block was below economic thresholds with 0.2 per cent codling moth, 0.2 per cent apple scab, 2 per cent of leaves with mites, and 14 per cent of leaves showing signs of canary fly.

South Australia: Joe Ceravolo at Ashton in the Adelaide Hills had participated in the release of the codling moth parasitoid Mastrus ridens in May 2018 as part of the PIPS 2 project. The block was under mating disruption in the 2018–19 and 2019–20 seasons to capitalise on the low codling moth populations after the release of Mastrus. Moth trapping results are presented in Figure 2. In 2019–20 the first cohort of generation 1 was very small and no insecticides were sprayed. The second cohort reached a peak of five moths/trap and some damage was evident, prompting a spray in mid-January 2020 targeted at the second generation. Damage recorded at harvest was 0.2 per cent for codling moth and 0.8 per cent for apple scab. Damage attributed to loopers was 4.6 per cent. Loopers are an early season pest and sometimes difficult to detect before they cause damage.

Figure 2: Moth captures in Ceravolo case study over two years

In Lenswood Kym Green is transitioning to organic certification after practising biodynamic principles for several years. He had no problems with WAA or apple scab in 2019–20. His main pest problem was control of codling moth with applications of granulosis virus. Unfortunately, the Adelaide Hills fire that burned into Lenswood had a big impact on Kym’s orchard and we were not able to complete a harvest assessment of pest and disease damage.

 Western Australia:  Mark Scott, at Nannup, had been experiencing issues with Bryobia mites, apple dimpling bug, WAA, and snails. He used ducks to control the snails. They did a good job but need to be locked up overnight to protect them from foxes. A green-tip oil spray controlled the Bryobia mites. WAA were managed by distributing parasitised colonies into hotspots. Spring beetle was a problem in some varieties but was controlled with spot spraying to limit impact on beneficials.  Alternaria caused 3.2 per cent damage, bitter rot 1 per cent, powdery mildew 0.6 per cent, weevils and mealybugs 0.4 per cent each.

In Kirup, not far from Mark, Terry Martella had recognised that some of his mite problems from previous seasons may have been due to the disruptive effects of Klartan sprayed to control dimple bug. He dropped Klartan from his program for some blocks and had no problems with dimple bug. Apple scab was not a problem despite a wettish spring. Terry made an interesting observation that mites started a month earlier than normal in blocks with darker netting.

Manual online

The long-awaited revision of the IPM Manual for Australian Apples and Pears will be translated into online format and published on the webpage in coming months.

The new manual has an increased emphasis on integrating cultural and biological control options using appropriate aspects of conservation biocontrol and regenerative agriculture to improve soil health and reduce pest, disease and weed populations by increasing the range of generalist predators/parasitoids present in the orchard. There are new sections on biosecurity, weed management, and pesticide resistance.

The decision to implement IPDM is very much a personal decision driven by the historical context and current aspirations of the orchardist. Therefore, a single recipe for IPDM will not work for all growers. The manual addresses this by providing strategies rather than prescriptive recipes.

The project set out to increase grower knowledge and confidence in IPDM decision making. To measure improvement the team conducted an initial survey of the industry and a follow up survey to quantify any changes will have been circulated by the time this article goes to press. Please check the link on the website and provide your input if you have not already done so.

Next steps

Hort Innovation has approved a further levy-funded project Strengthening cultural and biological management of pests and diseases in apple and pear orchards as part of the new PIPS3 program  that will allow further development of this work. The new project will include more elements of IPDM, including the importance of integrating weed management and conservation of biocontrol agents.

Biosecurity IPDM

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