Featured

Last year at the IOBC conference on greenhouse IPM in the UK, we were talking with Dr Richard GreatRex, field development manager with the UK biocontrol company Syngenta Bioline, about visiting a large greenhouse vegetable producer with a successful IPM history and he suggested Hedon Salads in Yorkshire. This interested us as Marilyn had previous history with the company going back almost 25 years and we were keen to learn of their progress in that time.

See More

We caught up with long-time friend and colleague Neil Helyer at a recent IOBC conference on greenhouse IPM R&D developments in the south of England. We reported on the conference in the previous issue of PH&G. These conferences, held every 3 years, always have farm visits, which are opportunities to see how EU and UK greenhouse hydroponic growers are progressing with their IPM programs. This year was no exception, with successful IPM on display in a range of different crops.

See More

In September 2011 we made the long haul across the pond to England to attend an International Organisation for Biological Control (IOBC) workshop, specifically, a meeting of the Western Palaearctic Regional Section, Temperate Climate Working Group for Integrated Control in Protected Crops. This is a bit of a mouthful but distinguishes it from several other regional and crop- or pest-specific working groups under the auspices of the IOBC. See More

The authors explore the evidence for neonicotinoid impacts on honey bees, the role of governments in regulating pesticides, and the changes required to adequately evaluate their environmental safety.

By Marilyn Steiner and Stephen Goodwin See More

In this two-part article, the authors shine a spotlight on neonicotinoid pesticides against a backdrop of widespread use of this group and concerning reports of an alarming and increasing loss of biodiversity. While honey bees have been the focus of concern, other pollinators and invertebrates, birds and even the lowly earthworm are at risk.

Part I examines neonicotinoid uses in Australia and problems ascribed to their use overseas, particularly massive losses of honey bees. Are honey bees under threat from colony collapse disorder in Australia? Are we equipped to adequately address environmental pesticide management issues?

By Marilyn Steiner and Stephen Goodwin
See More

External view of pad and fan system.

(Image courtesy Elly Nederhoff)

If you have a greenhouse you definitely need to think about ventilation. Effective greenhouse ventilation is a very important function to produce a consistent quantity of high-quality produce.

Article by Wouter Claassens

Modern consumers demand produce that is consistently uniform with respect to aspects such as colour, taste, appearance, shape, shelf life and so forth. The closer the produce meets consumer expectations, the higher the quality of the produce and the higher the price the consumer is willing to pay. For the long-term financial survival of a commercial greenhouse operation, it is therefore of paramount importance to produce a consistent quantity of high quality produce.

Effective climate control is a very important step towards producing produce that meet consumer demands. The design of a climate control system would need to be able to modify the outside climate in order to create the ideal inside climate. Ventilation of a greenhouse is the factor that has the single biggest influence on effective climate control within a greenhouse. To fully understand this point, it is necessary to investigate the role of airflow around a plant. See More

The newly launched ‘Truss Me’ campaign sees the coming together of some major industry players to boost consumer awareness of vine-ripened, hydroponically grown tomatoes.

By Christine Paul

Truss tomatoes are sold on the vine or ‘truss’ – the longer a tomato is left on the vine, the sweeter and tastier it is. The tomatoes are easily identified by their green truss, which acts as a mark of freshness. The tomatoes should remain on the truss until ready to be consumed, as the truss continues to feed water and flavour into the fruit, maximising its juiciness and taste.

High in lycopene – which research suggests may reduce the risk of prostate, pancreatic and cervical cancer – truss tomatoes also contain calcium and vitamins C, E and A, minerals and vitamins that help the body to absorb iron and contribute to healthy skin, muscles, hair, bones and teeth. The tomatoes are also a good source of fibre, which is known to benefit the digestive system as well as lower cholesterol.

This autumn, leading truss tomato growers d’VineRipe, Moraitis and Blush have increased production to keep up with increasing demand for flavoursome, high quality tomatoes. Truss tomatoes fill the bill for this demand from consumers for quality and have an excellent reputation for being full of flavour, albeit they are sold at a slightly higher price than their field-grown counterparts. However, it’s a price that most increasingly foodie-conscious consumers are willing to pay in their quest for premium produce.

In an innovative joint initiative, three of the major players have teamed up to launch a new campaign – ‘Truss Me’ – in a bid to increase consumer awareness and education about truss tomatoes as well as drive sales.

At the initial round of discussions, another industry leader, Flavorite, was also considering its move to join the three companies spearheading the ‘Truss Me’ campaign. The company has, however, since decided against doing so, citing costs of promotional investment and other factors as a deterrent.

The effect of various growth mediums on the development and production of plants in hydroponics systems.

By Ben Safronovitz

In a trial conducted at Camdeboo Farm near Fourways, Johannesburg, South Africa, one basic question was posed. Are there any differences in the overall performance of plants grown in different growing mediums? …The reason for the trial is the general uncertainty (at least in South Africa) regarding growing mediums. Many growers are confused or reluctant to use some mediums due to a lack of experience, lack of performance information, and/or an ignorance regarding the financial implications of using the medium in the short- and long-term.

The main objective of a grower is to invest the minimum possible in infrastructure and achieving the maximum yield, which in financial terms means increased profit. Therefore, in the short-term, investing in an inferior growing medium is a reality. The fact is that a larger initial investment will in the long-run return an increased yield per growing cycle to warrant the investment, and yield a greater profit.

In South Africa sawdust as a hydroponic medium is used extensively; it is inexpensive, readily available from a nearby mill, and due to its low-cost, can be discarded after each growing cycle.

The importance of understanding the characteristics of a growing medium and the long- and short-term affect on the plant is essential to the overall success or failure of a crop, therefore the trial targeted the most commonly used growing mediums in the country, each on its own (to serve as a control batch) and also in combination with other growing mediums. Without elaborating on the physical and chemical differences among the tested growing mediums, each has characteristics, which make it a usable medium – for example: bulk density, porosity, aeration, ability to contact water with high holding capacity, highly hygroscopic, create capillary water and nutrients dynamics, etc.

The mediums used for the purpose of this trial were:
•    Palm pith (Coir) 100%
•    Perlite 100%
•    Vermiculite 100%
•    Sawdust 100%
•    Palm pith 50% / Perlite 50%
•    Palm pith 70% / Perlite 30%
•    Palm pith 40% / Perlite 30% / Vermiculite 30%
•    Perlite 50% / sawdust 50%
•    A locally produced light compost pot soil 50%  / Perlite 50%

Growing medium trials at Camdeboo Farm near Fourways, Johannesburg.

A standard tunnel 30m x 10m was selected for the purpose of the trial, positioned north-south with excellent light cover during the day. A white/black ground cover plastic sheet was used to eliminate weed growth and increase light reflection at the tunnel floor level, thus increasing plant photosynthesis.

Day one – seedlings transplanted into medium.

Medium consists of 50% palm pith and 50% Perlite.

Seedlings in 100% sawdust.

Seedlings grown in 50% pot soil and 50% Perlite.

Seedlings grown in 100% Perlite.

Seedlings grown in 100% Vermiculite.

Perlite 50% Sawdust 50%

The trial principles of using one crop (tomato), one cultivar (Malory – indeterminate variety produced by Mayford-Sakata seeds), under the same climatic conditions and nutrient feed and irrigation cycle regime across the various mediums, allowed a fair and  unbiased evaluation of the plants’ performance during a complete growing cycle.

The hydroponics method used was quite revolutionary, which is in the process of patent registration. In essence, the method uses growing containers with a slit on one side at a certain level. This method allows routine irrigation (four times daily) of approximately 800 cubic centremetres of water and nutrients per plant on average, which has enormous implications on cost in terms of saving water and nutrients. The growing system was an open system (not re-circulated) and the drain kept to 10% of the total volume.

The floor plan was organised to allow for eight rows of 48 containers each. One block of 48 containers served as a control, representing each of the tested mediums. There were 432 containers with two plants per container, a total of 864 plants. Each medium covered a block of 48 containers situated along the tunnel width to ensure fair distribution of light or shade across the eight rows, eliminating the possibility of false results due to uneven exposure to light.