Categories
Supporting Services

Diffused Light

Diffused Light

 

Diffused glass and diffused coatings are available.  Diffused coatings are relevant for our current structures. 

The best example I have seen to understand the effects on diffused light is; that direct light either has its leaves in the light or the dark.  The proportion of leaf surface that is lit becomes less deep within the crop.  The leaves of a plant in diffuse light have at a certain height a better horizontal distribution of light, (so shadows don’t exist) the light intensity does reduce as it goes deeper into the crop.

Photosynthesis is greater if light is distributed horizontally over a surface area than when light falls just on one spot.  The effect is compounded because better photosynthesis leads to greater surface area which also leads to more photosynthesis. 

Diffused coatings should have a high transmission and haze factor.  The transmission % determines the light which falls on the crop.  The less the transmission the more the lights degree of scattering, which will mean that light is sent off in all directions and means a limited amount falls onto the crop.  The haze factor is the degree of scattering of the incoming light.  Too my understanding the haze factor should be 50% and the hemispheric transmission should be 83% when choosing diffused Glass.

Diffused light will help create a more uniformed climate by having a better photosynthesis plants will transpire more from their leaf area which is the greenhouse cooling system, this will increase humidity and therefore is decreasing the stress on the plant because it is able to keep cooler.  You could find your leaf length could increase.  This does not mean vegetative in the summer it just means plants will be stressed less giving them a more comfortable environment to thrive in. 

 

When is a good time to apply diffused coatings?  This summer with our extremely warm hot dry weather would have been the perfect opportunity to get good results with diffused coatings.  I would have thought that even in a New Zealand summer which had indifferent weather that diffused coatings would still be beneficial as when the cloud disappears and the sun appears it can be extreme!!  It has been noticed that in the heat of the day when our sun is intense and our light levels are intense, crops that are under diffused light don’t go into respiration and keep transpiring and working, this is where the gains in higher yields and quality can come from.  We have extremely high light intensity in the summer and can go from 200 watts to 12 watts in five minutes!!  This will happen regardless if we have a wet or dry summer.  Anything that will help the plants through these highs and lows must be beneficial.  I have always noticed that Cucumbers grown in plastic houses during the summer to do better than in glass houses, one factor could be the effect the plastic has on reducing the intense direct light transmission from a glass house? The other factor could be water availability and low stem density in glasshouse cucumber summer crops.

At what crop stage should you apply diffused coatings?  This is a tricky one, do you wait until your crop is under stress or do you apply it before it shows signs of being stressed and what happens if your crop doesn’t show signs of stress??  Crop registration figures and fruit loading should give you an indication of plant vigour.  You could also use this to look for a trend, for example the leaf length slowly decreasing and stem thickness decreasing.   It is never just one thing however, applying diffused coatings will help if a plant is stressed, but it will could be because of an overloading of fruits per m2 or a root/health issue before you need to use a diffused coating.  On the flip side if you don’t have an old or weak plant and it is vegetative (too low a fruit load), possibly diffused coatings won’t make it work hard enough?

Diffused coatings in the winter will mean glasshouses will heat up slower and therefore you will need more heating, you will also need to change your irrigation strategy as your plants will ‘start’ slower so uptake and transpiration will be reduced.

Diffused coatings could reduce light by 10% but increase transpiration in the summer months, (sounds Irish, that’s why it has taken a long time to figure this stuff out.  An Irish man would be buggered!!)  In the winter you will have 10% less light and reduce transpiration in the morning and evening periods.  I have been told that you will still get more production in the winter with diffused coatings but I do wonder what the extra energy costs would come too.  Another potential adverse effect if your greenhouse is heating up slower in the winter time, is potential extra condensation leading to extra fungal issues?

Like anything with new technology, it will take time for us all to figure it out.  I definitely see the merits of using this product on glasshouses in the summer and see the payback being well worth it.  The spray on coatings will work best if they are sprayed on evenly!!!

 

 

Please contact Stefan Vogrincic at Grower2Grower for more advice.

 

Article Written by Stefan Vogrincic Grower2Grower 

Categories
Industry Profile

From High School Teacher to Tomato Grower

From High School Teacher to Tomato Grower

 

James and Jae Kang have been growing tomatoes for the NZ market since 2001.  How and why this happened is truly a moving story.

James grows the tomato variety Alfred from Monsanto in his plastic house.  The variety suits the greenhouse and crop cycle.

 

Originally from Korea, James and Jae decided to immigrate to New Zealand in the late 1990’s.  Jae and James met at university in Korea in the 1980’s.  They married and started their family together, they have two children a son and daughter.   Their son, Taewon, was born with severe autism as well as intellectual disabilities. 

Their decision to immigrate was reached as they felt the environment, to care for Taewon, were limited in Korea, and New Zealand offered a brighter future for him. 

 James likes growing Merlice in the 1400 m2 glasshouse.  It is compact in nature and suits the height of the glasshouse as well as the added bonus of a high yield potential.

 

 

James and Jae Kang have been growing tomatoes for the NZ market since 2001.  How and why this happened is truly a moving story.

Originally from Korea, James and Jae decided to immigrate to New Zealand in the late 1990’s.  Jae, a high school art teacher, and James, a high school maths teacher met at university in Korea in the 1980’s.  They married and started their family together, they have two children a son and daughter.   Their son, Taewon, was born with severe autism as well as physical disabilities.  He has the behavioural age of a 2-3-year-old.

Their decision to immigrate was reached as they felt the facilities, to care for Taewon, were limited in Korea, and New Zealand offered a brighter future for him. 

In 1999 Jae came to New Zealand with the children, they lived in Henderson for 6 months before James could leave Korea to join them.  I can’t begin to imagine how hard this would’ve been, living in a foreign country, the language barrier as well as caring for a severely autistic seven-year-old and nine-year-old daughter.  To highlight how difficult it was for Jae, Taewon would never sleep for more than 3 hours at a time, once he was awake for 5 consecutive days and nights!

In 2000 James joined the family in New Zealand.  He looked into the teaching profession and began to gain the necessary qualifications.  It was extremely difficult for James to pass these papers with limited English.  James could’ve spent a few more years qualifying as a high school math's teacher, but after an introduction to a Korean greenhouse grower he and Jae looked at the option of purchasing a business growing tomatoes in Waiuku.

This appealed to James for two reasons; the language barrier he had at the time, and it would give him flexibility to help Jae with Taewon, who needed 24-hour care and supervision

In 2001 James and Jae purchased a property in Waiuku, South Auckland.  The property had a 1400 m2 Faber Greenhouse on it.  Since then they have been growing large, loose, round tomatoes for the local market.  In 2015 James expanded the operation by custom building another 1000m2 plastic house on the property.

I first met James in 2008, I fondly remember how clean and tidy his greenhouse was.  The plant work is always up to date and crop always strong and healthy.  In the early days James had to learn how to grow by talking to other Korean growers.  There is a strong bond between the Korean growing community and they always find the time to help each other.  On planting days, they all help each other plant, they have lunch together lunch and talk.  James noted how helpful Derek Scholfield and Steve Gellert, the owner of Gellert Nurseries, have been to him.

It was over the next 5 or so years, selling plants to James, that I realized he was not just a very good grower but that he was well respected amongst his peers.   James went on to become a part time Communications Assistant for Gellert Nurseries.  James undertook this role for 4 years and did a fantastic job. Unfortunately, due to the resignation of his assistant grower, he had to go back to work full time at his farm.

James and Jae have been growing since 2001, with no plans for retirement just yet.  James has a measured approach when it comes to growing.  He has become a very successful and respected grower, impressive for a maths teacher who had no previous growing experience before coming to New Zealand.

 

 

 

Jae has also become very well known for her Art work.  When Taewon was 21 he went into residential care (he returns home on weekends) Jae decided to go back to University to study and refresh her passion for art, she is currently finishing a post-graduate diploma at Elam School of Fine Arts.   Jae has combined her sculptural background with her Korean drawing technique, creating what Jae describes as “drawing installations”

 

Jae uses recycled irrigation lines to create some amazing sculptures which are displayed at art galleries all across the country.   Jae welcomes people to touch her sculptural work, in the hope to give the opportunity to people with impaired vision to get a sensory touch to art.

 

James and Jae are truly remarkable and selfless, both immigrated to a foreign country for their children, setting up a new business in a totally unfamiliar industry is a truly inspiring story.  They have contributed hugely to New Zealand and we are better off for having migrants like James and Jae here.  They are the perfect example of devoted parents willing to work tirelessly to provide for their family.

I am so glad James and Jae decided to become growers, I have had the pleasure of becoming a colleague and friend of James.  I look forward too many more growing conversations with James in the future.

 

Article written by Stefan Vogrincic, Grower2Grower

Categories
Technical

Plant Maintenance Procedures

 

Plant Maintenance Procedures

This article describes techniques used for crop maintenance on Tomatoes and Cucumbers.

 

Tomatoes

 

CLIPPING OR TWISTING:

I estimate a 50/50 split between growers twisting plants up the string or clipping.Certain varieties dictate which procedure growers use.Plants that grow upright are easier to twist compared to plants growing away from the string.Plant vigour is a reason why growers sometimes use both techniques.The trick to twisting plants is to not over twist but not to leave bows.When clipping make sure not to put the clip directly above the truss.As a guideclip underneath the first leaf below each truss.Sometimes you have to add extra clips between the trusses because of potential bowing.

DROPPING/LAYERING:

How much you drop the plant depends on your cycle.Seven day cycles between twisting/clipping and dropping should be the target, in reality the average would be 7-9 days.The amount you drop the plant will vary from week to week, my preference is to lower to roughly the same level each time. It is very important when staff are layering they try to evenly space the heads so each plant can capture the same amount of light. Remember to check crop wires are also spaced correctly as this is important.

 

DE-LEAFING:

Breaking leaves is common. If they do not break cleanly scars and stubs may be left behind which create a pathway for disease.

Cutting leaves, with a knife, is now very common.I prefer this method as you have a nice clean wound every time. My advice is to sterilize your knife every 5-10 plants.If you are using a knife it doesn’t matter if you cut the strings as the clips further up the plant will stop the plant from falling.

TRUSS SUPPORTING AND TRUSS PRUNING:

Keeping this as a separate job can be very useful.The attention to detail is far better.If you grow a variety that requires a specific number of fruit per truss then I recommend this option.

TRUSS REMOVAL:

Ripping or cutting trusses are the two options.Ripping can leave a huge scar.Cutting is easier, but if you don’t cut the truss close to the stem, you could leave small stubs which will be another potential entry point for disease.If you harvest truss tomatoes sterilize cutters between every plant.Especially if you have varieties susceptible to bacterial canker.

 

 

Cucumbers

 

TWISTING:

It is very important to do a tight twist on cucumber plants.If there are too many bows your plant could slip down the string when the fruit is becoming mature, which could break the stem.Having the opportunity to twist twice a week is important.Cucumbers grow rapidly; if you do not twist regularly more damage, in the form of broken heads, may occur.Managing the labour with cucumber crops is very important.

 

UMBRELLA SYSTEM:

Terminating the head of the plant at the top of the wire then growing two laterals back to the ground is common.At certain times of the year, some varieties do not grow two strong laterals.If the plant is in balance, and you have thinned correctly, you have the option of growing the main head back down – leaving a side shoot from a node close to the wire to grow down also.

Layering cucumbers is also an option which not all growers consider.It can be done very successfully.It could also give you the option of taking laterals earlier and growing with more stems per m2 for a longer period of time.

 

 

These are systems I am all extremelley familar and experienced with.  Please contact Grower2Grower via the commercial grower section for advice tailored for your situation.  Terms and conditions apply.

Technical aritcle written by Stefan Vogrincic Grower2Grower

Categories
Irrigation/Substrates Supporting Services Technical

Intelligent Plant Monitoring

Trutina, plant weight monitoring system 

Cultivation presents considerable challenges to growers, including the method of irrigation, which is crucial to successful production. Different growing platforms possess different water storage and rewetting abilities due to their density, special compound, substrate type and size. Efficient irrigation scheduling provides plants with sufficient water for desired production and quality while minimizing water losses. Specialists agree that varieties with great genetic potential are unable to produce higher yield without a proper irrigation strategy.

 

Plants need healthy and constantly renewable root system with suitable amount of oxygen in the growing platform. To be able to reach optimal level of growth, they need controlled change in the water content in accordance with the time of the day. The change of water content triggers vegetative or generative impulses in the plant. To keep the balance within the plants, accurate and reliable control needed. The optimal water content depends on the time of the day and by following a couple of rules, our plants can be successfully managed.

 

The timing of the first morning watering has a great effect on the plants. The effect of irrigation on plants is primarily determined by the difference between the highest value of water content during the last watering of the previous day and the water content value of the first watering the following morning. To maintain the balance of the growth rate this value should be between 6% and 12% in greenhouses with climate control systems. This difference can be smaller in the case of growing facilities with considerable daytime/night-time fluctuation in temperature, so that the vegetative effect of the growing platform containing more water could compensate the generative effect of the higher difference in temperature.

 

Infoboard 

 

Trutina, a weight monitoring system is a great tool for improving greenhouse control and strategy, making production significantly more efficient resulting in higher production yields and major cost savings. The system consists of a hardware unit and cloud based software. It enables customers to follow plant weight (biomass) in real time, weight trends of a separate growing substrate with hanging or platform based method, showing related supporting info (biomass production, plant activity, plant energy balance etc.). The unit can calculate the necessary amount of irrigation and drain tendency as well, which enables irrigation planning. Tutrina has been tested and can be used for tomatoes, capsicums and cucumbers.

 

 

 

The device stores the measured data and continuously uploads them to the Cloud, the information then can be viewed on your computer or smartphone and the dashboard surface can be fully customised.

 

 

 

RNR Limited is currently offering a 3 months trial for the first Grower to get in touch.                                

 

For more information and contact details, please visit www.rnr-ltd.co.nz.

 

 

Categories
Greenhouse News

Crop Fries and Dies

Vent malfunction causes crop loss

 

Every grower’s nightmare has come true for a local grower.  A malfunction with the vents has meant a tomato crop, which was still three weeks from picking, has been fried.  I am unsure how long the vents were closed, before they were fixed and reopened, but as you can see from the picture the damage caused was devastating.  The crop has literally been cooked.  

Even if you have an alarm system, unless you are close by, even a short period with such intense temperature can cause irreparable damage to your crop.  If it is a power outage then having a generator is going to avoid this situation but a blown fuse, on a circuit board or something more serious, is a different kettle of fish.  Particularly if you are not able to isolate the problem quickly and if you are not on site during the day.  If the outage occurs on a public holiday it could be difficult to get your sparky on site quickly.

Many years ago, I was in a similar predicament- we had lost power, it was in the middle of the summer, and early one morning.  The vents were down, as it was a cool morning, but I knew it would heat up very quickly, and by the time I could get a generator on site for my sparky to hook up I knew the temperature of the greenhouse would detrimentally affect the crop.  Luckily we had a socket set handy and Dad could climb up to the vent motors and manually open the vents.  From memory it took around 15 minutes to get one of the vents open manually, but it was very handy to know when all else failed we could physically open the vents. However, the outcome could very easily have been the same as the picture below. 

 

Half of the house was cucumbers and they were also devasted.  

 

If it was a blown fuse and no one was on site to replace it, for several hours, your crop would be in serious trouble.  It places the importance of being on site at all times during the day, or having someone regularly pop in to check. Please ensure you have all the tools required handy and know the process to manually open your vents.  If you don’t know how to do this please contact your greenhouse manufacturer to find out how this can be done.  An event like this is a disaster and I never wish this upon any grower to have this type of catastrophe but if this article will help prevent another grower from this situation then it is definitely worth writing.

 

I appreciate your comments.  Please feel free to comment below or on the grower2grower Facebook page:

https://www.facebook.com/StefanGrower2grower/

Article Written by Stefan Vogrincic, Consultant, Grower2Grower

Categories
Greenhouse News

February ’15 – A Great Loss

In January New Zealand lost one of the best tomato growers in the country. Sadly Jeff van Rijen lost his battle to cancer. My sincere condolences go to all of Jeff’s family.

The Photo to the Right shows Jeff (on the right) with his brother Frank.

If you did not have the pleasure of knowing Jeff I can tell you that he was not just a great grower but a great decent kiwi bloke. Cancer has robbed us of one of the good guys at such a young age.  He was committed to his work but first and foremost he was a family man.

I was introduced to Jeff by Matthew Heller (a former tomato grower) when Jeff was still a teenager. My mentor at the time, Bryan Hart, along with Mathew allowed me to join a crop discussion group with the van Rijens. In reflection joining the crop discussion group was one of the most important factors to aid my development in the tomato growing industry. I was very fresh and I do remember being lost quite often in the early days with the technical jargon. Tony van Rijen, Jeff’s father, was brilliant and I would invariably pick things up from him every time we met. For Jeff as a teenager I suspect it was also good to have someone not too much older than him in the group.

In the late 90’s we started visiting 3-4 times a year, we generally did this from autumn to spring as summer was always too busy. We would take turns travelling to and from Hamilton to visit Tony and Jeff. Over the years we continued to keep our visits up, when Matthew retired and Tony semi-retired Jeff and I continued to visit each other. When I started working for Gellert Nurseries we continued to visit each other, we even started visiting Great Lakes in the Taupo district together.  

I will fondly remember all our car trips together. One thing we had in common was tomatoes, we could talk from Hamilton to Taupo and then from Taupo back to Hamilton about tomatoes!  When we were in the greenhouse we would talk about tomatoes!  It was not for one minute boring and I will miss those car rides and the crop walks immensely. We played golf together a few times; I remember playing 18 holes of golf and all we did was talk about tomatoes and his poor putting! I also had the pleasure of dining with Jeff at numerous tomato functions and events over the past 15 years. Jeff had a great eye for growing which he learnt from his father Tony. Jeff could read plants and understand, by sight, what was happening at different times to his crop. Together with his dad Tony and brother Frank, the Van Rijens have always been the highest winter producers of tomatoes per m2 I know. They are a huge part of the modernisation of tomato growing in New Zealand. They were the pioneers in growing in rock wool in NZ, they were one of the first to grow grafted plants and then advanced 60cm flowering plants from the nursery, and if we did not get it 100% right Jeff would let me know as he wanted to keep me on my toes! 

Jeff also loved his greenhouse toys and would love showing them off, he was especially proud of his roof washer and his plant removal equipment.

We have lost an innovative bright brilliant grower who just happened to be a great guy. I will miss you and our friendship we have had over the past 15 years.  Rest in peace.