Aubergines Jaylo RZ / Gabriella RZ - week 51, 2009

For most growers December means: planting aubergines!
The majority of glasshouses will have been planted up again by the end of the week. According to the new trend, after initially only tomato plants, a lot of aubergine plants are now also grafted above the seed leaves. Just as last year on that single nursery, it is looking good on all the nurseries now. It does give about 2 cm extra in crop height in the glasshouse but, and that is more important, there will be less growth (suckers and the like) from the rootstock.

Changes in cultivar have been very few. The Jaylo area has settled down at 56 ha. The other varieties have also remained reasonably similar in size. The large increase in Gabriella did not materialise, but the area of 1 ha in 2009 has increased to 5.5 ha for 2010, so this variety is given another chance to prove itself. There is one entire glasshouse planted up with the variety and it will be seen again in various trials. The new rootstocks, including our variety 61-074 RZ, will also have to prove themselves in 2010. The total aubergine area of heated substrate crops in the Netherlands and Belgium has grown by 4 ha this season, from 104 ha to 108 ha. We are only talking about the oval aubergine types here. We cannot say very much yet about the Turkish, long aubergines, for most of these crops have yet to be sown.

Start of the crop
The slabs have mostly been saturated with an EC of 3.0 - 3.5 mS. Lower also occurs but on those nurseries the plants often have a very light head and also more often glassiness or water spots. So a higher EC does give a more robust plant that is most likely also less susceptible to weakness parasites, which could, for instance, attack the roots now. Something we also notice is that one or two plant raisers are watering with a higher EC, sometimes as high as 5.0 mS. This also has a positive effect on the plant quality. A plant like that has often been raised with steady temperatures, has a nice green colour, is compact and the roots will often have no difficulty in penetrating the slab.
Depending on the EC value in the slab, water with an EC of 3.0 - 4.2, so that the EC value in the slab works out at around 3.5 - 3.8 mS. The higher EC value may be chosen for Gabriella because it is more important with this variety to create a generative plant.

The watering frequency differs quite considerably between nurseries. An early planting (end November) in rockwool can often need no more than 1 - 2 watering rounds per day at 100 or 70cc each, if the screen remains closed. Plants that have not been on the nursery for more than 1 - 10 days can be watered more frequently in order to keep the contact area between block and slab moist enough, to make it easy for the roots to get into the slab. For rockwool you could put on 3 - 4 watering rounds in the daytime and for perlite 6 - 10 would be more appropriate, including a night watering round. Small rounds of about 50 cc each would work best as it gives the water time to warm up and there does not need to be too much run-off.

Screens
The mobile cloth screens have stayed closed this week on virtually all nurseries because of frost. It is all right to open the screen in November plantings during the lightest hours of the day (between 11.00 am and 3.00 pm, in line with radiation), as these plants already have more transpiration capacity so that it does not cause the relative humidity to drop too low too quickly. Neither is it a big problem in these crops if the day temperature temporarily drops below 21°C, for the heads will only become stronger with this extra light with the screen open. Some extra reserves in these heads now can ensure later that a little bit of extra fruit speed can be created by using afternoon temperature increases in January.

For December planters it is a matter of keeping up the temperature so as not to slow down the crop too much; level 22°C for the first few weeks with 3 stems until the head really becomes too thin or 'hare's ears' occur. If you are going to use the 4-stem system, it would be better to reduce the temperature slightly, i.e. level 21°C, as Jaylo tends to skip a head a little easily if the crop's condition is weak (incidentally, you would get it back in March, though). However, if you want to be one of the first on the market with the 4-stem system, come hell or high water, you will have to be resigned to the fact that you will have to pay for that later in extra labour when it comes to twisting a branch to make the 4th stem.

Biology
Our last bit of advice, partly based on the experiences of the previous growing season, is to start clean - we cannot emphasise this too much. The first thrips have already been spotted on one or two nurseries, only 10 days or so after increasing the temperature, and they are best eradicated at an early stage. Treating the glasshouse 3 - 4 times with approved products will be done a lot this year. This can often save a lot of worries, because leaving it till a couple of weeks later can cause problems for the natural predators, which should be, or have been, released by then. It is also easier, of course, to hit everything now, than when everything is hiding in the flowers.

The aubergine crop team of Rijk Zwaan send Season's Greetings and wish you a prosperous 2010.

Crop advice given by the seller is not binding. Descriptions and recommendations in these crop tips are as accurately as possible based on experiences in trials and practice. We do not, however, under any circumstances accept any liability for deviating results of the product grown in accordance with such information. The buyer needs to satisfy himself that these crop tips are suitable for his local conditions and the crop he intends to grow.