Fruit size and harvest costs

Picking costs are one of the biggest items in a strawberry operation.  Anything that reduces picking cost will make a strawberry growing operation more profitable.

Speed of picking is one of those factors, but there are a lot of variables that affect that.  How well the fruit is displayed, how much of it is on display at any one time, how good the picker is, how easy the fruit is to remove are all factors.  We believe that fruit size is one of the keys.

Logic suggests  that it’s faster to pick big fruit than small fruit.  Growing big fruit is therefore likely to be more profitable.  There is surprisingly little published research work on this, so we decided to see if we could put a number to berry size impacts on picking rate.

Talking with seasoned strawberry growers, we have landed upon 30 kg/hour as a reasonable average picking speed.  Yes, it ranges widely from a low end of 10kg/hour to a high end of 45 kg/hour.  Yes, whether packing is included in this process or a separate packing line is used is also variable.  But for sake of calculation, we are choosing to work with 30kg/hour.  An individual farm’s hourly cost of labour can be calculated from that, but for sake of the calculations, we will assume the hourly cost of labour is $30 ($23.50 wages, plus holiday pay, ACC, overhead, etc).

We have found in our variety trial harvest data that picking speed varies directly with berry size.  If it 30kg can be picked/hour at 30 gram fruit, then 20 gram fruit, reduced in size by 1/3, can be picked at about 20kg/hour.  This makes sense intuitively, as each berry requires the same hand picking motion no matter how big or small it is.

‍So, what’s the value of big fruit?

Pretend we have 100 meters of row, with plants at 8 plant/meter, so 800 plants we’re picking.  Pretend we get 1 kg/plant which means 800 kg/100 meters.

Clearly, berry size is a really important factor.

There are several management factors that can increase fruit size:

1. Chose varieties with naturally bigger fruit
2. Increased plant spacing
3. Optimize plant nutrition and watering
4. Reduce high heat in summer

There is a cost associated with changing these factors, so it’s useful to think about how much they can be worth if fruit size was to increase.

If I could increase my average fruit size by 5g over the season, from 20g to 25g, my harvest cost would reduce by $240/100m, saving $20,000 per hectare in picking costs.