May 2018

Grower talk

Harvesting is our main focus at the moment. This includes regular contact with our agents to check supply and getting feedback from the markets

The warmer autumn weather means more watering and fruit fly remain active. Finishing off baiting for fruit fly is a top priority in mandarins in relation to pest management.

Maturity testing for imperials to exceed BrimA is next.

The citrus canker outbreak is a concern and we are keeping a close eye on developments.

Climate update and outlook

A drier start to the season is more likely on the southern productions regions of WA while in Kununurra, there is a 55% chance of exceeding rainfall for the period, June to August. For temperature, Most of WA has equal chance of warmer or cooler temperatures. there is a more than 60% chance of warmer days for the coastal regions of WA. Shrinking region further to south of Perth 60% chance of cooler

Evaporation and irrigation

Average daily evaporation rates for the coming month of June are: Harvey 2.1 mm, Karnet 1.6 mm, Gingin 2.1 mm and Carnarvon 3.8 mm. A large citrus tree (14 metre square canopy area) will use an average of 15.5 – 20 litres of water each day during June in the south-west and 37 litres in Carnarvon.

For more information on seasonal outlooks:

Crop status and management


GA Applications for rind quality

For maximum delay of rind aging and extension of harvest apply 10 ppm GA at colour break. This may delay colour development by 20 to 30 days. Ten parts per million of GA applied at 10‑50% colour may delay colour development by 10–15 days. Note: Late navel colour development is more sensitive to GA than other navels.

Apply GA to Imperial mandarins at three-quarter colour for the management of watermark.

Internal maturity development

Monitor development of internal maturity of fruit closely and ensure fruit meets at least the minimum Australian Citrus Quality Standards before harvest. Supplying fruit that does not meet these standards places poor eating quality fruit into the mouths of consumers. The resulting consumer backlash has impacts on the entire citrus industry. A granulation chart has also been developed for Imperials. WA citrus fee-for-service payers can have the internal quality of fruit independently tested without charge (two samples per variety per grower). Just drop your samples to any agent at Market City, Canning Vale.

Harvest timing

Think carefully about the timing of harvest as this can have a significant impact on the rind quality of the current crop and on flowering and fruit set for the next season. A late harvest for any given variety will reduce flowering the following season, particularly in many mandarin varieties. For mandarins, have an early select pick, taking the largest and most coloured fruit first. This takes the load off the tree and allows the remaining fruit to increase in size.


Oleocellosis is rind damage resulting from rough picking and handling of fruit. Damage does not fully appear for up to 4 days after the injury/damage occurred and can significantly reduce the value of your fruit. To minimise oleocellosis, harvest in the warmest part of the day and pick from the northern side of the tree first. As a rough guide, ambient air temperatures should be above 12°C, however a wet bulb temperature and rind oil release pressure test should be conducted to provide a more reliable guide. It is best not to harvest if fruit are wet.

Preparation for flowering

After harvest consider foliar applications of urea and micro nutrients to promote flowering for the next season particularly if you suspect a light flowering year.

Pest, diseases and weeds

Continue to monitor fruit fly levels and control with bait sprays, expecially as dry warm autmn keeps flies active. Be prepared to increase baiting frequency and density if trap numbers indicate the need.

Monitor scale and mealy bug and apply oil spray to infested areas when crawlers are active. This will help you take the correct action when determining control programs for the spring and summer period when juveniles of these pests are active.

Monitor for citrus gall wasp. Galls will start to become more visible on the spring flush from last season.

This Seasonal Update for Western Australia has been prepared by Bronwyn Walsh, WA Citrus.