PSTVD UPDATE

If you are a fresh tomato grower, you will have received an email from TomatoesNZ in December about Potato Spindle Tuber Viroid (PSTVd) being found in greenhouses in the South Island. This is a further update on the situation and a reminder about good hygiene practices.

You are probably aware that this was not the first time that PSTVd has been found in New Zealand tomato plants. Previous incidences were irradicated, and GIA (Government Industry Agreement for Biosecurity Readiness and Response) partners have pursued this same outcome for the most recent cases. The three infected greenhouses were stripped of all plants in December with all material buried on site, under Ministry for Primary Industries (MPI) direction, thoroughly disinfected and then replanted. As you can imagine, this was a stressful situation for the grower involved but they worked with the GIA partners and were fully compliant with the MPI directives. In terms of the source of this infection, the seeds tested negative and plant matter from outside of the greenhouses has to date also tested negative. It is likely that the source of the infection will never be known. As with all potential infections and incursions, it is better to be prepared and over cautious. While some PSTVd infected plants may show no signs at all, others could display some of the following symptoms:

• a lower-than-normal yield

• stunted spindly growth

• fruit not ripening

• spots or streaks of dead tissue on fruit

• yellow, purple or grey leaves which can roll up or die.

Clothes and on-site laundry as part of hygiene practices?

You might have seen an article published by In Greenhouses magazine on the benefits of clean workwear. Research has shown that clothes, including shoes, are a source of contamination when workers move around the greenhouse, with some viruses living on material for over a month. This has led some businesses to not only provide full work clothes for their staff, including shoes, but also for these items to be removed and laundered on-site.

For best hygiene practice it is recommended that dirty clothes are removed and placed in one room, moved to the washing machine and then the dryer, and exit at the other end of the laundry to a ‘clean room’ for folding and storing. Ensuring that dirty and clean clothes do not come into contact with each other is essential. Some businesses even go to the length of banning personal items like phones, earphones and caps or hats as these also pose a possible contamination risk. The cost of such measures must always be weighed up by each individual company, but as any grower who has had to destroy crops due to an outbreak of disease will tell you, the costs of having good hygiene practices cannot be underestimated.

Reverse decay whitefly trial

TomatoesNZ is looking to set up a trial that will test a number of different insecticides for whitefly that are not registered for tomatoes (i.e. are currently used off label) to determine what withholding period is needed to meet the default New Zealand Maximum Residue Limit (MRL) of 0.1mg/kg. This will help growers to know how long they need to wait after spraying before crops can be harvested. To set up this trial we need a trial site within a greenhouse that can be fully handed over to the trialist for approximately ten weeks over winter this year. This will include heavy use of insecticides, so will require a greenhouse that does not have beneficial insects in it, and the crop will need to be destroyed after the trial has been completed.

We also want suggestions of insecticides to use during the trial – do you have one that you would like to be included?

Conferences

The Horticulture Conference will be held in Christchurch from 1 August to 4 August 2023. Please mark this date in your diaries now. The date and time for the TomatoesNZ conference is yet to be confirmed but it will be part of the Horticulture Conference.

Please send suggestions and questions to dinah.cohen@hortnz.co.nz as soon as possible.

To book a classified advertisement in our next issue contact:

Debbie Pascoe (09) 2363633, M: 0274 858562 Email: debbie.pascoe@hortnz.co.nz

MatMan

Specialised Glasshouse Equipment For Sale

Commercial glasshouse grower / company in liquidation has for sale specialised glasshouse equipment, all unused, in original packaging, on pallets as follows:

Dehumidifiers: 4 X Quest 706, Made in USA, Capacity 335 litres/day, Efficiency 3.4 litres/kWh, Supply voltage 230V, 50 Hz Current Draw 18.6 Amps. Overhead or ground placement, MERV 13 filtration.

Lights: 86 x Fluence by Osram VYPR 3p, Grow light Broad 3R spectrum, 400 volt PSU2. Output 1680 umols, AC power consumption 618 Watts, each light includes 1 PSU power source, cables, Unistrut wire hangers.

All inquiries and bids welcome. Willing vendor.

If interested contact: Phil McKinstry

Palliser Insolvency Limited phil@palliserin.co.nz

021 280 2890