AgTech and Precision Agriculture to set and measure crop load and fruit size

Precision orchards

Precision Agriculture and AgTech are being used to set crop load and measure fruit at harvest such as fruit size, fruit number, yield, and fruit quality distribution profiles of different crop load management practices (chemical, mechanical, hand thinning).

On this page:

Introduction
Video: Blossom thinning and impacts, example from apricot trials.
2024/25 season crop load results
- apricot 'Golden May'
- nectarine 'Rose Bright'
- peach 'August Flame'
- nectarine 'Autumn Bright'
- plum 'Angeleno'

Introduction

The project is developing profitable management strategies for summerfruit growers associated with temporal and spatial variation in crop load, fruit quality (fruit number per tree, fruit size and colour), and labour use efficiency.

Through trials at the Tatura SmartFarm, this project will demonstrate the value of precision crop information and data-driven spatial ‘zonal’ crop load management (chemical, mechanical and hand thinning) geared to tree size to provide fruit growers with objective data for decision-making.

Scans of commercial orchard blocks will provide ‘real world’ examples of spatial data on crop load, fruit size, fruit colour, yield and tree vigour and size.

AgTech trialled for measurements in the orchard:

a ground based cartographer for scanning tree size, fruit size, fruit number and blossom loads,
hand held smartphone apps to measure fruit size and fruit number,
airbourne drone system to measure fruit number, fruit size, tree size and blossom loads.

Precision Agriculture on crop load trials:

Cropload trials are occurring on apricot, plum, nectarine, and peach comparing
- the Darwin string mechanical thinner
- manual fruitlet thinning
- precision pruning and hedging
- chemical flower thinning

Blossom thinning and impacts, example from apricot trials

Video: Dr Mark O'Connell talks about blossom thinning in apricots in the Stonefruit Experimental Orchard at the Tatura SmartFarm (Autumn 2025)

Research in the orchard with Dr Mark O'Connell, Agriculture Victoria Tatura SmartFarm

Video transcript

Hello, it's Mark O'Connell from Ag Vic Tatura Smart Farm, and I'm standing in the Tatura Trellis experimental stone fruit orchard, and we're about to harvest our Golden May apricots. And what we've been doing this season is using AgTech and precision agriculture to set the crop load and measure the crop load and fruit size.

We have technologies like the ground base cartographer that scans the fruit and the trees. We have handheld apps that use the three camera systems and LiDAR systems and smart algorithms to determine fruit size, fruit number. And we're also testing, once we get it deployed, a airborne system using a drone to measure fruit number, fruit size, canopy size.

And what we've done this season, at the experimental stone fruit orchard, is use mechanical flower thinning with the Darwin thinner. We've used some chemical thinning systems, and we've used manual hand thinning, plus unthinned treatments. So, we're about to compare at harvest time, the final fruit size, final fruit number yield, and fruit distribution profiles of these different experimental treatments.

And now it's after harvest. We've had a chance to put that fruit over the fruit grader. We've also done orchard scans with the cartographer and produced heat maps of fruit size, fruit colour, fruit number, et cetera.

Looking at some of the data we can see we had a whole range of responses with fruit number per tree ranging from 200 fruit, a tree right through to 450 fruit per tree, and that induced a range of fruit sizes responses, and yield responses.

For example, the Darwin thin treatment plus plant growth regulator, ATS at a low rate, produced the least amount of fruit per tree, which responded in fruit size being larger at harvest, but at the penalty of a low yield.

Apricot case study

Blossom thinning using a combination of chemical thinners (ATS - a plant growth regulator) and mechanical thinner (Darwin string) increased final fruit size due to reduction in fruit number per tree.

Similarly, hand thinning at fruitlet stage produced a high proportion of large fruit (fruit diameter greater than 46 mm).

Chemical thinning alone (using ATS) at full bloom had minimal effect on final fruit number or fruit size in season 2024/25.

Graph: Apricot Crop load management comparing various blossom and fruitlet thinning techniques

Proportion of large fruit size in response to crop load management using various blossom and fruitlet thinning techniques in apricot 'Golden May' on Tatura Trellis at the Tatura SmartFarm, season 2024/25

Apricot fruit weight versus fruit per tree

Fruit size and fruit yield in response to crop load management using various blossom and fruitlet thinning techniques in Apricot 'Golden May' on Tatura Trellis at the Tatura SmartFarm, season 2024/25

2024/25 season crop load results

Yield and fruit quality results from crop load studies:

APRICOT ‘GOLDEN MAY’

Table 1 outlines the experimental crop load (blossom and fruitlet thinning) treatments under a Tatura Trellis canopy system for apricot ‘Golden May’ in season 2024/25 at Tatura, Victoria, Australia.

Table 2 presents production results (yield, fruit quality) for apricot ‘Golden May’ in response to crop load treatments for season 2024/25.

In summary, the early season apricot ‘Golden May’ produced medium sized (≈ 30 g) fruit and yielded 6.3 kg/tree when grown under a medium crop load (hand thinned treatment) regime. The 0.5_ATS+Darwin treatment resulted in the lowest crop load, whereby low final fruit number increased fruit weight and fruit diameter, increased yield, and no effect on fruit skin colour (CDI 0.65). The Darwin treatment alone improved fruit colour (CDI 0.68).

Treatment	Rate (% v/v)	Timing (% bloom)	Method
Table 1. Crop load (blossom and fruitlet thinning) treatments under a Tatura Trellis canopy system for apricot ‘Golden May’ in season 2024/25 at Tatura, Victoria, Australia.
ATS_0.5	0.5	100	Sprayer
ATS_1.0	1.0	100	Sprayer
ATS_1.5	1.5	100	Sprayer
Darwin	-	100	Mechanical
Unthinned	-	100	-
Hand	-	Fruitlet	Manual
ATS denotes plant growth regulator, Ammonium Thiosulphate.

Treatment	Fruit number (#/tree)	Yield (kg)	Fruit weight (g)	Fruit diameter (mm)	Fruit colour (CDI)
Table 2. Yield and fruit quality performance statistics in response to crop load treatments of apricot ‘Golden May’ under a Tatura Trellis canopy system during 2024/25 season.
ATS_0.5	396 _c	9.9 _a	25.0 _a	40.4 _a	0.63 _ab
ATS_0.5+Darwin	222 _a	8.0 _b	36.2 _b	44.0_b	0.65 _abc
ATS_1	385 _c	9.4 _a	24.5_a	40.3 _a	0.63 _a
ATS_1+Darwin	303_abc	7.8 _a	25.6_a	40.6 _a	0.66 _abc
ATS_1.5	371 _c	9.3_a	25.0 _a	40.4 _a	0.63 _ab
ATS_1.5+Darwin	249 _ab	7.1 _a	28.4 _a	41.5_a	0.66 _bc
Unthinned	335 _bc	8.8 _a	26.8 _a	41.0 _a	0.63 _ab
Darwin	307 _abc	9.5_ab	31.4 _ab	42.5_ab	0.68 _c
Hand	214_a	6.3 _ab	29.6 _ab	41.9 _ab	0.65 _abc
ANOVA	***	***	***	***	***
nd, ns, , * and *** indicate not determined, non-significant or significant differences at P < 0.05, 0.01 or 0.001, respectively. CDI denotes colour development index (scale: 0 – 1). Different letters within a group suggest that those data are significantly different from each other.

NECTARINE ‘ROSE BRIGHT’

Table 3 outlines the experimental crop load (blossom and fruitlet thinning) treatments under a vase canopy system for nectarine ‘Rose Bright’ in season 2024/25 at Tatura, Victoria, Australia.

Table 4 presents production results (yield, fruit quality) for nectarine ‘Rose Bright’ in response to crop load treatments for season 2024/25.

In summary, the early season nectarine ‘Rose Bright’ produced medium sized (≈ 70 g) fruit and yielded 20 kg/tree when grown under a medium crop load (hand thinned treatment) regime. The ATS_1.5 treatment resulted in a crop load similar to hand thinning, whereas lower rates of ATS fail to reduce fruit number per tree. Hand thinning reduced fruit skin colour (CDI 0.83) compared to other treatments.

Treatment	Rate (% v/v)	Timing (% bloom)	Method
Table 3. Crop load (blossom and fruitlet thinning) treatments under a vase canopy system for nectarine ‘Rose Bright’ in season 2024/25 at Tatura, Victoria, Australia.
ATS_0.5	0.5	100	Sprayer
ATS_1.0	1.0	100	Sprayer
ATS_1.5	1.5	100	Sprayer
Unthinned	-	100	-
Hand	-	Fruitlet	Manual
ATS denotes plant growth regulator, Ammonium Thiosulphate.

Treatment	Fruit number (#/tree)	Yield (kg)	Fruit weight (g)	Fruit diameter (mm)	Fruit colour (CDI)
Table 4. Yield and fruit quality performance statistics in response to crop load treatments of nectarine ‘Rose Bright’ under a vase canopy system during 2024/25 season.
ATS_0.5	473 _ab	24.2	78.7	46.6	0.87 _b
ATS_1.0	445 _ab	23.8	73.7	47.5	0.87 _b
ATS_1.5	380 _a	20.0	55.5	47.5	0.87 _b
Unthinned	506_b	25.4	51.4	46.3	0.87 _b
Hand	370 _ab	20.0	77.5	46.8	0.83 _a
ANOVA	*	ns	ns	ns	***
nd, ns, , * and *** indicate not determined, non-significant or significant differences at P < 0.05, 0.01 or 0.001, respectively. CDI denotes colour development index (scale: 0 – 1). Different letters within a group suggest that those data are significantly different from each other.

PEACH ‘AUGUST FLAME’

Tables 5 and 6 outline the experimental crop load (blossom and fruitlet thinning) treatments under a Tatura Trellis and Vertical Leader canopy system, respectively, for peach ‘August Flame’ in season 2024/25 at Tatura, Victoria, Australia.

Tables 7 and 8 presents production results (yield, fruit quality) for peach ‘August Flame’ in response to crop load treatments for season 2024/25 under a Tatura Trellis and Vertical Leader canopy system, respectively.

In summary, the midseason peach ‘August Flame’ produced medium sized (74 - 81 g) fruit and yielded 6.5 and 12.0 kg/tree when grown under a medium crop load (hand thinned treatment) regime, under Vertical Leader and Tatura Trellis systems, respectively. Combinations of Darwin thinning treatments resulted in the lowest crop loads, whereby low final fruit number increased fruit weight and fruit diameter at the expense of yield. The ACC treatment did not reduce fruit number compared to the unthinned treatment. All crop load (blossom and fruitlet thinning) treatments had no effect on fruit skin colour (CDI ≈ 0.75).

Treatment	Rate (% v/v)	Timing (% bloom)	Method
Table 5. Crop load (blossom and fruitlet thinning) treatments under a Tatura Trellis canopy system for peach ‘August Flame’ in season 2024/25 at Tatura, Victoria, Australia.
ATS_0.5	0.5	100	Sprayer
ATS_1.0	1.0	100	Sprayer
ATS_1.5	1.5	100	Sprayer
ACC	350 ppm	100	Backpack
Darwin	-	100	Mechanical
Unthinned	-	100	-
Hand	-	Fruitlet	Manual
Plant growth regulators; ATS (Ammonium Thiosulphate) and ACC (Accede).

Treatment	Rate (% v/v)	Timing (% bloom)	Method
Table 6. Crop load (blossom and fruitlet thinning) treatments under a Vertical Leader canopy system for peach ‘August Flame’ in season 2024/25 at Tatura, Victoria, Australia.
ATS_0.5	0.5	100	Sprayer
ATS_1.0	1.0	100	Sprayer
ATS_1.5	1.5	100	Sprayer
ACC	350 ppm	100	Backpack
Darwin	-	100	Mechanical
Unthinned	-	100	-
Hedge	-	Midseason	Mechanical
Hand	-	Fruitlet	Manual
Plant growth regulators; ATS (Ammonium Thiosulphate) and ACC (Accede).

Treatment	Fruit number (#/tree)	Yield (kg)	Fruit weight (g)	Fruit diameter (mm)	Fruit colour (CDI)
Table 7. Yield and fruit quality performance statistics in response to crop load treatments of peach ‘August Flame’ under a Tatura Trellis canopy system during 2024/25 season.
ATS_0.5	181 _b	13.7 _c	76.1_ab	53.4 _ab	0.76
ATS_0.5+Darwin	82 _a	7.4 _ab	90.5 _b	56.3 _b	0.76
ATS_1	172_b	11.8 _bc	68.7 _ab	51.8_ab	0.74
ATS_1+Darwin	81_a	7.6 _ab	93.8_b	57.0 _b	0.71
ATS_1.5	192 _b	12.0_bc	62.5 _a	50.5 _a	0.74
ATS_1.5+Darwin	82 _a	7.6 _ab	92.9 _b	56.8_b	0.72
ACC	165 _b	12.0_abc	73.2 _ab	52.8 _ab	0.82
Unthinned	169 _b	12.0_bc	70.7 _ab	52.27 _ab	0.78
Darwin	76_a	6.1_a	80.6 _ab	54.3 _ab	0.78
Hand	146_b	12.0_bc	80.9 _ab	54.4_ab	0.72
ANOVA	***	***	**	**	ns
nd, ns, , * and *** indicate not determined, non-significant or significant differences at P < 0.05, 0.01 or 0.001, respectively. CDI denotes colour development index (scale: 0 – 1). Different letters within a group suggest that those data are significantly different from each other.

Treatment	Fruit number (#/tree)	Yield (kg)	Fruit weight (g)	Fruit diameter (mm)	Fruit colour (CDI)
Table 8. Yield and fruit quality performance statistics in response to crop load treatments of peach ‘August Flame’ under a Vertical Leader canopy system during 2024/25 season.
ATS_0.5	85 _c	5.4 _c	63.7 _ab	50.8 _ab	0.78
ATS_0.5+Darwin	18 _a	1.7_a	95.9_d	57.5 _d	0.78
ATS_0.5+Hedge	89 _c	5.8 _c	65.5 _abc	51.2 _abc	0.77
ATS_1	86_c	4.8_c	55.9_a	49.2 _a	0.76
ATS_1+Darwin	18_ab	1.4 a	78.6_bcd	53.9_bcd	0.77
ATS_1.5	98 _c	5.6 c	56.6_ab	49.3_ab	0.75
ATS_1.5+Darwin	22_ab	1.6_a	76.9_abcd	53.5_abcd	0.73
ATS_1.5+Hedge	75_bc	5.0_abc	65.6_abc	51.2_abc	0.76
ACC	84_c	5.3_bc	63.8_ab	50.8 _ab	0.76
Unthinned	88_c	5.5_c	61.6_ab	50.4_ab	0.76
Darwin	19_ab	1.8_ab	90.7 _cd	56.3 _cd	0.80
Hand	90_c	6.5_c	74.0 _abcd	52.9_abcd	0.76
ANOVA	***	***	***	***	ns
nd, ns, , * and *** indicate not determined, non-significant or significant differences at P < 0.05, 0.01 or 0.001, respectively. CDI denotes colour development index (scale: 0 – 1). Different letters within a group suggest that those data are significantly different from each other.

NECTARINE ‘AUTUMN BRIGHT’

Tables 9 and 10 outline the experimental crop load (blossom and fruitlet thinning) treatments under a Tatura Trellis and Vertical Leader canopy system, respectively, for nectarine ‘Autumn Bright’ in season 2024/25 at Tatura, Victoria, Australia.

Tables 11 and 12 presents production results (yield, fruit quality) for nectarine ‘Autumn Bright’ in response to crop load treatments for season 2024/25 under a Tatura Trellis and Vertical Leader canopy system, respectively.

In summary, the midseason nectarine ‘Autumn Bright’ produced medium sized (70 - 77 g) fruit and yielded 6.2 and 12.5 kg/tree under a Vertical Leader and Tatura Trellis system, respectively, when grown under a medium crop load (hand thinned treatment) regime. For the Vertical Leader system, combinations of ATS, ACC and/or Darwin thinning treatments resulted in lower crop loads, whereby low final fruit number increased fruit weight and fruit diameter at the expense of yield (Table 4). Whereas, on Tatura Trellis system the crop load (blossom and fruitlet thinning) treatments resulted in minimal differences in fruit quality outcomes (Table 3).

Treatment	Rate (% v/v)	Timing (% bloom)	Method
Table 9. Crop load (blossom and fruitlet thinning) treatments under a Tatura Trellis canopy system for nectarine ‘Autumn Bright’ in season 2024/25 at Tatura, Victoria, Australia.
ATS_0.5	0.5	100	Sprayer
ATS_1.0	1.0	100	Sprayer
ATS_1.5	1.5	100	Sprayer
ACC	350 ppm	100	Backpack
Darwin	-	100	Mechanical
Unthinned	-	100	-
Hand	-	Fruitlet	Manual
Plant growth regulators; ATS (Ammonium Thiosulphate) and ACC (Accede).

Treatment	Rate (% v/v)	Timing (% bloom)	Method
Table 10. Crop load (blossom and fruitlet thinning) treatments under a Vertical Leader canopy system for nectarine ‘Autumn Bright’ in season 2024/25 at Tatura, Victoria, Australia.
ATS_0.5	0.5	100	Sprayer
ATS_1.0	1.0	100	Sprayer
ATS_1.5	1.5	100	Sprayer
ACC	350 ppm	100	Backpack
Darwin	-	100	Mechanical
Unthinned	-	100	-
Hedge	-	Midseason	Mechanical
Hand	-	Fruitlet	Manual
Plant growth regulators; ATS (Ammonium Thiosulphate) and ACC (Accede).

Treatment	Fruit number (#/tree)	Yield (kg)	Fruit weight (g)	Fruit diameter (mm)	Fruit colour (CDI)
Table 11. Yield and fruit quality performance statistics in response to crop load treatments of nectarine ‘Autumn Bright’ under a Tatura Trellis canopy system during 2024/25 season.
ATS_0.5	197	11.6	59.4 _abc	49.9_abc	0.81
ATS_0.5+Darwin	174	14.1	81.3 _d	55.2_d	0.82
ATS_1	196	10.6	54.7 _a	48.8 _a	0.83
ATS_1+Darwin	174	12.3	70.8_abcd	52.6_abcd	0.83
ATS_1.5	198	11.6	60.0_abc	50.1 _abc	0.83
ATS_1.5+Darwin	149	10.5	70.3_abcd	52.5 _abcd	0.83
ACC	232	12.2	52.6 _ab	48.3 _ab	0.82
Unthinned	189	11.1	59.2 _abc	49.9 _abc	0.83
Darwin	139	10.4	74.7_cd	53.6 _cd	0.81
Hand	179	12.5	70.3 _bcd	52.5 _bcd	0.82
ANOVA	ns	ns	***	***	ns
nd, ns, , * and *** indicate not determined, non-significant or significant differences at P < 0.05, 0.01 or 0.001, respectively. CDI denotes colour development index (scale: 0 – 1). Different letters within a group suggest that those data are significantly different from each other.

Treatment	Fruit number (#/tree)	Yield (kg)	Fruit weight (g)	Fruit diameter (mm)	Fruit colour (CDI)
Table 12. Yield and fruit quality performance statistics in response to crop load treatments of nectarine ‘Autumn Bright’ under a Vertical Leader canopy system during 2024/25 season.
ATS_0.5	108_c	7.1_bc	66.2_ab	51.6_ab	0.85 _bc
ATS_0.5+Darwin+Hedge	50 _ab	4.1_ab	81.8 _def	55.3 _def	0.83_ab
ATS_0.5+Hedge	104_bcd	7.1_abc	68.2 _abcd	52.0 _abcd	0.85_abc
ATS_1	101_c	7.1_bc	69.8_abc	52.4_abc	0.85_bc
ATS_1+Darwin+Hedge	45_ab	3.7_ab	84.2 _ef	55.9_ef	0.83_ab
ATS_1.5	106_c	7.2_bc	68.8 _abcd	52.2_abcd	0.86 _bc
ATS_1.5+Darwin+Hedge	33_a	3.1_a	94.8 _f	58.4 _f	0.81 _a
ATS_1.5+Hedge	96 _bc	6.9_abc	71.8_abcde	52.9 _abcde	0.86_bc
ACC	82_abc	5.8_ab	71.4_abcd	52.8_abcd	0.85_bc
Unthinned	163_d	10.1_c	62.5 _a	50.7_a	0.87_c
Darwin	55_abc	4.4_ab	81.0_cde	55.1_cde	0.83 _ab
Hand	80_abc	6.2_ab	77.3_bcde	54.2_bcde	0.86_bc
ANOVA	***	***	***	***	***
nd, ns, , * and *** indicate not determined, non-significant or significant differences at P < 0.05, 0.01 or 0.001, respectively. CDI denotes colour development index (scale: 0 – 1). Different letters within a group suggest that those data are significantly different from each other.

PLUM ‘ANGELENO’

Table 13 outlines the experimental crop load (blossom and fruitlet thinning) treatments under a Tatura Trellis canopy system for plum ‘Angeleno’ in season 2024/25 at Tatura, Victoria, Australia.

Table 14 presents production results (yield, fruit quality) for plum ‘Angeleno’ in response to crop load treatments for season 2024/25.

In summary, the late season plum ‘Angeleno’ produced medium sized (≈ 43 g) fruit and yielded 7.9 kg/tree when grown under a medium crop load (hand thinned treatment) regime. Combinations of ATS and/or Darwin thinning treatments resulted in the lowest crop loads, whereby low final fruit number increased fruit weight and fruit diameter at the expense of yield. The ACC treatment did not reduce fruit number compared to the unthinned treatment. All crop load (blossom and fruitlet thinning) treatments had no effect on fruit skin colour (CDI ≈ 0.82).

Treatment	Rate (% v/v)	Timing (% bloom)	Method
Table 13. Crop load (blossom and fruitlet thinning) treatments under a Tatura Trellis canopy system for plum ‘Angeleno’ in season 2024/25 at Tatura, Victoria, Australia.
ATS_0.5	0.5	100	Sprayer
ATS_1.0	1.0	100	Sprayer
ATS_1.5	1.5	100	Sprayer
ACC	350 ppm	100	Backpack
Darwin	-	100	Mechanical
Unthinned	-	100	-
Hand	-	Fruitlet	Manual
Plant growth regulators; ATS (Ammonium Thiosulphate) and ACC (Accede).

Treatment	Fruit number (#/tree)	Yield (kg)	Fruit weight (g)	Fruit diameter (mm)	Fruit colour (CDI)
Table 14. Yield and fruit quality performance statistics in response to crop load treatments of plum ‘Angeleno’ under a Tatura Trellis canopy system during 2024/25 season.
ATS_0.5	225_de	9.7 _de	43.3_a	40.6 _a	0.82
ATS_0.5+Darwin	106 _ab	4.60 _ab	43.6 _abc	41.5 _abc	0.83
ATS_1	181_cd	7.9_cd	43.6_abc	41.7 _abc	0.81
ATS_1+Darwin	71_a	3.1_a	43.9_bc	42.9_bc	0.80
ATS_1.5	180_cd	7.9_cd	43.8 _bc	42.5_bc	0.81
ATS_1.5+Darwin	77_a	3.4_a	44.0 _c	43.5_c	0.81
ACC	271_e	11.8_e	43.5_abc	41.3_abc	0.83
Unthinned	264_e	11.4_e	43.1_a	39.6_a	0.85
Darwin	161_bc	7.0_bc	43.4_ab	40.9_ab	0.80
Hand	182_cd	7.9_cd	43.5_ab	41.1_ab	0.83
ANOVA	***	***	***	***	ns
nd, ns, , * and *** indicate not determined, non-significant or significant differences at P < 0.05, 0.01 or 0.001, respectively. CDI denotes colour development index (scale: 0 – 1).

Acknowledgements

This project Precision summerfruit orchards (SF23000) has been funded by Hort Innovation, using the Summerfruit research and development levy, contributions from the Australian Government and co-investment from Agriculture Victoria. Hort Innovation is the grower-owned, not-for-profit research and development corporation for Australian horticulture.