Defoliation - it's nice when things just work

30 April, 2018


After the horror story of 2017, it’s been a refreshing change to see bolls opening and leaf falling off cleanly and quickly as we finish defoliation for this season. Going into defoliation, the forecast was for good conditions – temperatures were above average mostly across the board and there really wasn’t any rain in sight.

There’s been an increase in the use of ground rigs for first passes this year. Again, after experiencing such difficulty defoliating the crop last season, many growers and their consultants were on the front foot with what could be done differently. The improved product penetration from a ground rig was appealing, and with a 36m boom the overall risk of loss from cotton being knocked to the ground was small. In fact, anecdotally I’ve heard very little concern with this being a problem after that first pass.

Compaction is always a concern and we’ve been lucky (in this regard) that is has been so dry to allow ground rig defoliation to be an option. The warm dry weather has also been in our favour as top bolls have matured nicely, where they have been able to hold on. There was a substantial amount of top crop lost in the second main heat wave of the season back in February, this coupled with very high thrip numbers may have had an impact. Early March rain also resulted in top regrowth, particularly in earlier crops.

The relative ease of defoliation this year really highlights the isolated issues that we experienced last year. Whilst another hot dry summer, those extreme temperatures which resulted in damage to the abscission layer in 2017 didn’t eventuate this season. But the challenges of last year did out us on the alert to go in with a slightly different strategy this year – by all reports it seems to have paid off.

By Alice Devlin, Extension & Development Agronomist – Gwydir Valley.