Newsletter cucumbers

Crop tips week 39 - 2011
for. among others, Bonbon RZ, Roxanna RZ, Euphoria RZ and Proloog RZ

General
September was fairly dark but ends with a 'summery' week which will last until 3/4 October. Productions have dropped faster in recent weeks than we would have liked; this goes especially for July plantings. The present good weather has meant renewed growth and production. Productions of the autumn crops are slightly lower than we are used to. The disease pressure has also been a little greater up till now due to the weather conditions in August and September. That's why we've heard about more problems than usual with, for instance, pythium and stem botrytis up till now.

Working towards a good finish of the crop
Now that autumn is with us we must try and make the most of the speed in the crop for as long as ever possible, so maintain a high enough temperature in the crop. In order to prevent that the gas consumption rises (too much), using the screen is entering the picture again. The screen may be closed when the outside temperature is 8°C or lower, as long as it goes hand in hand with a min. pipe of 45°C. A gap of a few per cent should take care of any excess moisture. Even with these set points we see that crops become exhausted sooner. Especially if yours is an older crop (planted in July), you will notice that within the next two weeks the crop will really be getting towards the end. Be careful, therefore, if you want to continue cutting good cucumbers until some time in November, that you don't use the screen too much. In that case, use the screen only during the warming-up phase, for instance, and when the pipe needs to be more than 55°C and/or the outside temperature is below 5°C. Growing still equals investing in the crop and that also applies, therefore, to continued cucumber crops.
If you want to continue growing the crop well, a sufficiently high 24-hour temperature is vital from now on. It should be 20.5 - 21.5°C. Any lower will really give you old, bad cucumbers and ages the crop even faster. The vent position in the morning also needs your attention, because especially on a clear morning you can let the cold in. One degree between the temperature and ventilation set points is very well possible. Should the sun be able to help some, then let it, and an increase in the afternoon to a maximum of 27°C would be a very acceptable temperature; it will also give some speed and help towards the 24-hour temperature.

Disease pressure
Every grower is well aware that it is essential to finish a crop as cleanly as possible, especially where red spider mite and whitefly are concerned. This year we have seen more than one sizeable red spider mite outbreak on our travels and these should by now have been totally eradicated, or else a suitable preparation will have to be used to do so now.
Mosaic virus is the other nuisance. There are nurseries where it appeared for the first time this year. Draw up a thorough plan now for the crop change-over. There are plenty of examples of measures to be taken and working methods to be used. Discuss this with your advisor or study group and we, too, will be only too pleased to assist. This year again, there are nurseries that have managed to remain (virtually) mosaic-virus-free, even though last year it was quite widespread there. It's not surprising, then, that productions are up on last year where the virus has been kept away.

Feed and water
Just to complete the picture we'll also take a look at water and feed. The watering strategy should now be such that 'drowning' the roots is prevented but that they are kept active and able to transport feed to the plant. Watering on day dark could start 1 - 1 1/2 hours after sunrise (8.00/9.00 am). There's no rush to get run-off -- by the 3rd or 4th watering round is fine. Continue watering until 3.30 pm day dark and until 5.00 pm on day light. The size of the watering rounds, for standard rockwool, may be increased from 100 to 130 cc. If perlite is used the watering rounds are usually slightly smaller and slightly more frequent. Night watering rounds, however, will remain a rarity - possibly one following a very nice day and the the night is bright ...
Maintain a decent EC to guarantee a good colour for the final cucumbers. In the substrate we now like to see an EC of 2.8 - 3.2 and don't let the EC in the water drop any lower than 2.5. After all, we want to leave a good impression for next year with the last of the Dutch cucumbers, don't we?

Next season
Plans are being drawn up again for next season. With experiences of this year fresh in our minds we, at Rijk Zwaan, can tell you that we definitely want to be there with you again to help in choosing a variety for the first crop.

For early heated crops (planting December), Venice RZ still absolutely occupies the top spot on the varieties list. The high early fruit weight and its production capacity for the earliest crop are indisputably good. A newcomer for December plantings is 24-183 RZ.
Moving on, for January plantings, Proloog RZ is on many a grower's list of 'possibles' because this variety has proved itself convincingly were production and quality are concerned; suitable for a continued first crop as well.

Carambole RZ and Euphoria RZ are the other two trump cards for January crops and for these crops, too, the two varieties have a faithful group of followers who appreciate how easy they are to grow, their quality and production. And Carambole, with its combination of vigour and fruit set, is the variety we recommend for high-wire crops with planting dates in January and February.

Don't these varieties have any disadvantages at all, then? We don't think they do, but ...
There definitely are differences between the varieties, because growing conditions and growers'/buyers' demands are different. Our crop advisors will be only too pleased to discuss these matters with you in order to arrive at tailored advice. Do not hesitate to contact us.

All that remains for us is to wish you a good end to this growing year and much wisdom in your decisions for the next growing season.