GEM™ Avocados in New Zealand September 2019
Why GEM? 2 Seeka Grower Roadshow | December 2016
Avocados World Wide An industry with only slow improvements in productivity Unlike other high value fruit crops (apples, kiwifruit, berries, nuts etc) average avocado yields are similar to those 20 years ago There are new innovations in growing systems and technology but these are only slowly being implemented Why? 3 Seeka Grower Roadshow | December 2016
Avocado Industries are Largely Based on Hass A good variety but it has limitations Hass is a good variety for taste and shipping fruit Hass is high vigour and likes to alternate bear, tends to low yielding without significant management systems Best innovation to date has been high density planting, with Hass this is hard to do without Plant Growth Regulators and lots of pruning It would be great to have a variety with a growth habit that suits high density and has lower alternate bearing 4 Seeka Grower Roadshow | December 2016
GEM Attributes Positive characteristics for high density GEM has attracted attention as it: ▪ Has low vigour ▪ Compact growth habit ▪ Non-spreading ▪ Tolerates temperature extremes ▪ Very precocious ▪ Less alternate bearing ▪ Later maturity ▪ Very good taste ▪ Hangs late on the tree 16 year old tree ▪ Attractive fruit 5 Seeka Grower Roadshow | December 2016
GEM in NZ 8,500 trees planted in 14 orchards GEM is grown through a licence with Westfalia Estates the world-wide master licence holder There is a very enthusiastic group of early adopter GEM growers in New Zealand Over 8,000 more trees will be planted in September to November 2019 Sounds impressive but area is small (53 acres) as the trees are planted at 160 per acre at 19.5’ by 13’ (400 per hectare at 6m x 4m spacing) 6 Seeka Grower Roadshow | December 2016
Growing GEM We need to learn how to grow GEM Seeking to understand how to best grow GEM to get high yields of high quality fruit Starting at the beginning of a new industry so I am using the new plantings to learn as much as we can I have a flowering and fruit set monitoring programme for GEM like I do for Hass Investigating different canopy management ideas, expect canopy management to change as the trees age 7 Seeka Grower Roadshow | December 2016
Planted trees from December 2017 to April 2018 Summer and Fall in New Zealand The trees looked great…. …. to start with As time went by trees dropped leaves and started dying It was worse the later the trees were planted Trees on clonal rootstocks were the worst 8 Seeka Grower Roadshow | December 2016
Tree Decline Not typical of Hass, the roots were great Zutano 6 weeks after planting in March Dusa 6 weeks Dusa several after planting in weeks after December planting in March 9 Seeka Grower Roadshow | December 2016
Tree Decline Some leaf drop and very heavy flowering was expected The tree decline was very unusual The trees died from the top down and had very strong and healthy roots Pruning the trees killed them Lots of bud break from above the graft forming new growth There was no disease or pest associated with the decline The trees were all from the same nursery 10 Seeka Grower Roadshow | December 2016
Tree Decline Despite the leaf drop fruit set was OK 11 Seeka Grower Roadshow | December 2016
Tree Decline Despite the leaf drop fruit set was OK 12 Seeka Grower Roadshow | December 2016
Tree Decline New fruit had a red blush, too much sun? 13 Seeka Grower Roadshow | December 2016
Tree Decline Often new growth from above the graft 14 Seeka Grower Roadshow | December 2016
Tree Health Survey Assessed every tree over time Tree health survey, rating trees every few weeks Tracked rootstock and planting time Surveyed the growers for their management practices GPS mapped the location of every tree The worst affected trees were replaced the following spring at Seeka’s cost 15 Seeka Grower Roadshow | December 2016
GEM Mapping Individual trees GPS mapped after planting 16 Seeka Grower Roadshow | December 2016
Tree Health Scale 1 = Dead to 10 = very healthy 5 3 2 10 7 10 17 Seeka Grower Roadshow | December 2016
GEM Mapping Individual trees health rating 18 Seeka Grower Roadshow | December 2016
GEM Mapping Individual trees health rating 19 Seeka Grower Roadshow | December 2016
Planting Time and Rootstock Tree mortality Planting time Dusa Bounty Zutano December 2017 26.0% - overwatered 4.8% 4.0% February 2018 24.6% 15.6% March 2018 16.4% 6.0% 1.3% 11.6% 2.4% 54.3% April 2018 5.5% 0.0% 78.5% - end of April 19.4% October 2018 2.8% No of trees 3263 491 1219 20 Seeka Grower Roadshow | December 2016
Planting Time and Rootstock Observations Death followed leaf drop and excessive flowering in spring Would normally assume it was a root health problem This was wrong as the roots were healthy but….The root ball was smaller the later the planting ▪ December roots extended 1-2m (39” – 78”) ▪ February roots extended 1m (39”) ▪ March roots extended 0.5m (19.5”) ▪ April just past the root ball Healthy trees had a red flush while sick trees had a green flush suggesting nutrients were an issue Tree mortality was mostly on the Dusa rootstock Thickening/expansion of the trunk was a good sign the tree would survive no matter how bad the top looked 21 Seeka Grower Roadshow | December 2016
Tree Mortality Speculation on what happened Dusa is a high vigour rootstock GEM is a low vigour scion with high precocity Contrast with Hass a high vigour scion Bounty and Zutano are moderate vigour rootstocks Dusa has “grabbed” the carbohydrate and is using it for growth at the expense of the GEM flowers Effectively starving the GEM part of the tree as if the roots were damaged Hence the same symptoms as Hass trees that lose their roots 22 Seeka Grower Roadshow | December 2016
Planting Time and Rootstock Conclusions Plant Dusa rootstock October to December Plant Bounty and Zutano in spring and fall Be very careful not to overwater Apply foliar fertiliser every two weeks even in winter For excessively flowering trees remove flowers August/September, try and keep the vegetative bud Don’t prune trees Drench the soil around struggling trees with phosphorus acid 23 Seeka Grower Roadshow | December 2016
Foliar Fertiliser Nitrosol NPK (8:3:6) 24 Seeka Grower Roadshow | December 2016
Foliar Fertiliser Nutrikelp Plus This didn’t work very well Need to figure out the best foliar option by trial and error 25 Seeka Grower Roadshow | December 2016
Solid Fertiliser Young Trees AvoMix a blended granular fertiliser Applied at a small handful a tree monthly 26 Seeka Grower Roadshow | December 2016
GEM Leaf Nutrient Levels Comparison with Hass Nutrient GEM Hass So far little Nitrogen 2.6 2.4 difference Phosphorus 0.17 0.14 to Hass Potassium 1.2 1.1 % Calcium 1.4 1.4 Expecting Magnesium 0.29 0.37 to run GEM Sulphur 0.23 0.24 Zinc 32 35 at higher Boron 29 35 Nitrogen ppm Copper 10 43 than Hass Manganese 207 127 Iron 44 50 27 Seeka Grower Roadshow | December 2016
Quality issues Fruit scarring Two causes: Greenhouse Thrips and wind rub The skin is very sensitive when the fruit are young Good shelter is essential 28 Seeka Grower Roadshow | December 2016
Maturity as defined by Dry Matter GEM About one month later than Hass avocados However…… Seed coats were only fully mature in November Suggests harvest could start October/November for New Zealand grown GEM™ avocados 29 Seeka Grower Roadshow | December 2016
Maturity as defined by Dry Matter Average Dry Matter by Date Across Four Seasons Table 1. Average dry matter for 20 fruit samples collected from the GEM™ avocado trees in the Te Puke geneblock. Values are from the NZ Avocado Annual Research Report 2008 and Seeka measurements. Date Average DM (%) Seed coat % fully mature Average Fruit weight (g) 10/10/2006 28.9 233.2 12/1/2007 37.5 263.6 8/11/2007 31.9 243.8 20/11/2007 33.9 256.3 4/12/2007 34.6 235.7 18/12/2007 34.0 242.6 8/1/2008 37.7 253.2 25/9/2008 27.0 259.1 28/10/2008 29.5 273.3 31/10/2016 29.4 10 240.7 30/11/2016 34.2 100 261.4 9/1/2017 37.6 100 256.2 30 Seeka Grower Roadshow | December 2016
Maturity as defined by Dry Matter 2019 results Youngest trees have the earliest DM Library tray trial underway to define the DM standard for GEM in NZ 31 Seeka Grower Roadshow | December 2016
Tree Spacing 19.5’ x 6.5’ (left) vs 19.5’ x 13’ (right) 32 Seeka Grower Roadshow | December 2016
Tree Structures Berms and post and wire 33 Seeka Grower Roadshow | December 2016
Tree Structures Post and wire with strainer post 34 Seeka Grower Roadshow | December 2016
Tree Structures Post and wire no need for a strainer post 35 Seeka Grower Roadshow | December 2016
GEM Tree Monitoring Mark three shoots on each of 20 trees Follow flower bud break and development Timing of ovule initiation, flowering start, duration of flowering, fruit set Monitor the variability in phenology to make better management decisions Evaluate different flush types for fruit set success 36 Seeka Grower Roadshow | December 2016
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