Multiple Trials Show Benefits Of Plant Elicitor Approach.

g3 kiwifruit

Trials conducted in New Zealand and Italy show Agrizest helps to manage against the destructive impacts of Psa-V on kiwifruit vines and maintain high orchard gate returns in the disease environment.

Zest Biotech Chief Technical Officer Nathan Balasingham, who invented the formula, says Agrizest is not a cure for Psa, but it assists plants in their response to pests and diseases and environmental stress.

Since Nathan presented research results at the Psa 2013 International Conference at Mount Maunganui, a strong and expanding group of orchard owners and managers have kept Agrizest in their spray programmes each season.

Agrizest is able to be entered on orchardists’ monitored spray diaries as it is listed by Zespri as an “allowed other compound” and it is authorised by MPI (under the ACVM Act 1997) as exempt from registration. Agrizest is also certified by BioGro for use in Organic production.

There are 2 lists: Zespri Crop Protection Standard (CPS) and Allowed Other Compounds (AOC):

  • The CPS is only for products that are for the treatment of PSA. Zespri and KVH have decided that products can only be on this list if they are registered.

  • Products will only be registered by MPI if they are high risk i.e. they kill or harm other organisms (pesticides, herbicides, bacteriacides) or are hormones.

Agrizest is exempt from registration and appears on the AOC list and is ok to use for Zespri suppliers.

It should be seen as a positive that Agrizest is exempt from registration. Its not trying to kill Psa and smart growers know that trying to kill psa is fighting a losing battle.

Nathan, who has a Master of Science (Horticulture), with first-class honours in biochemistry, from Massey University and 36 years of experience as a researcher and in research and development management, invented the formula for Agrizest (and its pasture equivalent Biozest).

Zest Biotech’s products are manufactured in a proprietary designed plant at Pukekohe, Auckland. They hold their own against the purchasing and marketing power of some of the world’s largest agrichemical companies.

The key to the technology is that it helps plant to produce phenylpropanoids or essential oils, which are involved in protecting plants from light, ultra violet rays and heat damage, from mechanical, wind or hail damage, from damage caused by low temperatures, and by pests and disease.

“Phenylpropanoids also enable the plant to convert soil nutrients to a plant-available form. The phenolic hormone salicylic acid interacts with jasmonate and ethylene, and regulates the plants’ repair, growth and defence system,” Nathan says.

A split block trial conducted using Agrizest in a highly susceptible Hort16A gold orchard in the epicentre of the Psa epidemic in New Zealand in 2010/2011, showed the elicitor treatment increased yield by 21 per cent compared to the control. (Data available on request)

The market yield was much higher at 28 per cent, because the elicitor treatment also improved fruit quality. The net increase in returns to the orchardist was more than $17,000 per hectare. 

“The increased yield was not at the expense of fruit size. A higher proportion of the increase in yield was in the larger fruit size grade,” says Nathan. 

In a case study, a Katikati Hort 16A orchard which showed Psa disease symptoms in spring 2012 was successfully managed using Agrizest and Primazest with a record 22,000 trays per hectare in the low-diseased block, and 14,000 trays per hectare in the moderately-diseased block. The average fruit size was count 33, higher than in the industry average. 

“The high OGR ($210,000/ha) placed the orchardists in a strong financial position to replace the Hort 16A vines with a more resilient variety,” says Nathan.

Agrizest was also used on a seven-hectare Kiwifruit orchard in Aprilia, Italy. It decreased the impact of Psa on productivity. The orchard yield increased from 90 tonnes in 2010 to 280 tonnes in 2012.

“Trunk exudates decreased from 80 per cent to 60 per cent and in 2013 – only six vines had exudates and only on the laterals. The plants were under less stress and therefore the orchard saved on the irrigation bill by more than 500 Euros per hectare. The average fruit size also increased.”

Psa is a stress-induced disease. Nathan says there is an excessive use of fertiliser in the kiwifruit industry in New Zealand, which has led to physiological diseases and salinity problems.

Applications of excessive potassium fertiliser locks up the magnesium in soil particles and prevents adequate uptake, into the foliage. During the second stage of the growth cycle, the scarce magnesium in mature leaves is trans-located into the young leaves. Consequently, the older leaves suffer breakdown. High salinity in kiwifruit orchards is also resulting in premature leaf fall.

“Blocks treated with Agrizest are relatively free from leaf breakdown and premature leaf fall and have healthy productive leaves.”