Each target monitored by iMapPESTS for the Hart field site are presented in graphs separately for each week

These targets were identified as priority pests & diseases by the grains industry

Insect data is presented as the total number of each target insect counted in collected samples for each week

Spore data is normalised to 100% of the maximum counts detected of each target pathogen for each week

Aphids (green peach, Russian wheat and oat aphid) – A general trend of increasing winged aphid numbers is seen in response to the maturation and dying off of host plants (e.g. canola and cereals) forcing aphids to take wing in search of new green hosts. The decrease in aphid numbers in week 4 may suggest that most winged aphids have already found their new host or have died trying. The amount of green bridge available in the area will partially determine how well aphids survive over summer to reinfect crops in the new season.

What we found at Hart

Surveillance period

25/09/19 - 23/10/19

Green peach aphid (GPA)

Bird cherry oat aphid (BCOA)

Russian wheat aphid (RWA)

Western flower thrips (WFT)

Western flower thrips (WFT) – These introduced thrips are now ubiquitous in many Australian landscapes due to their wide host range. Whilst rarely an issue in the grains industry, they survive on some crops and build up populations that can impact on vegetable horticulture by the transmission of virus such as Tomato spotted wilt virus. As with aphids, warm weather and decreasing quality of host plants will prompt them to take to the air and be moved about in wind currents. In all the samples, the dominant thrips species was Thrips imaginis (Plague thrips) which may look similar to WFT but is far less damaging.

More aphids were collected in the 6m trap than the 2m trap. The shorter suction trap will generally provide information about the insects in the immediate paddock or property, whereas the taller 6m trap will mostly represent what is happening at a larger (potentially regional) scale. Insects captured from 6m height are mostly those that have been caught up in wind currents (small insects) or are flying a migratory pattern (larger insects). Given that insect pests are well managed at the Hart site, it is not surprising that the taller trap collects higher numbers as well as a greater diversity of insects. Additionally, the two insect traps use slightly different methods of suction which may impact on the number and type of insects captured.

Composition of traps

2m vs 6m trap results

Black leg of canola (Leptosphaeria maculans)

Botrytis grey mould (Botrytis cinerea)

Blackspot of field peas (Didymella pinodes)

Septoria

(Zymoseptoria tritici)

Spore release increased steadily over the 4 week period. This is likely driven by a rain event (10 mm) prior to week 1 & small rain event (2mm) at the end of week 2 causing subsequent spore maturation and liberation.

Maximum spore release was observed in week 2 & 4. Spore release is typically driven by leaf wetness periods, particularly from leaf debris on the soil surface.  

Spore release increased steadily over the 4 week period. This is likely driven by a rain event (10 mm) prior to week 1 & small rain event (2mm) at the end of week 2 causing subsequent spore maturation and liberation.

Maximum spore release was observed in Week 2 & 4. Spore release is typically driven by high humidity within crop canopy and wind events for dispersal.

iMapPESTS is led by Hort Innovation, through funding from the Australian Government Department of Agriculture as part of its Rural R&D for Profit program, with funding from 16 partner organisations