Chill Newsletter | Week commencing 27 July 2025

Morning All,

With strong bud movement in many varieties the season of chill accumulation is coming to a quick end. We will see theoretical chill accumulation but other than pistachios it is more daily temperature variances that play a significant role in bud movement. For those using dormancy breakers the more advanced the bud movement the lower rates of product should be used so to not damage the emerging bud.

If looking at the upcoming weather forecast and temperature differences between the maximum and minimum perfect conditions existed for flowering and strong bud movement on the 24/7. If I look at the coming weather for the next 7-10 days, we should see strong bud movement and flowering on those advanced varieties if looking at the temperature daily variance as the initiator of strong bud movement

Riverland: August 1-3

Mildura: August 1-3

Swan Hill: July 31-Aug 3

Griffith: August 1-2 and possibly July 31-August 1

With maximum temperatures being in the 15-16C range across all area’s bee movement will be low during these times. Watching my hives they are in the stay-at-home mode now.

I have included data over some recent seasons for comparative purposes as the chill season is rapidly ending except in Pistachios where the next 4-5 weeks is very critical for flower development.

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I thought it would be good to compare some data from previous years for comparative purposes.

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For the Riverland we go back to 2018 to have similar conditions and at least are along way off the horror chill years of 2003 and 2004 at Menindee where we had RCU in the 350-400 range on the 28^th.

One of the things to look at post set to determine how critical chill has been in influencing fruit set on your property.

• Time that the trees were placed into dormancy to bud swell (Were the trees dormant long enough?)
• In marginal chill conditions the E and NE facing sides of the tree will have a lower fruit set
• Check set on areas near wind breaks to see if higher crop loads exist based on the casting of shadows in the morning.

This may seem a bit pedantic but if you are in a corporate system crop phenology and chill data can be very useful in explaining crop variance to an accountant.

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Regards,

Shane Phillips | Head Chemist - Research & Development

E: shane.phillips@biocentral-labs.com

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