Maintype	Substrate
Crop	Tomato
Croptype
Variety	Arvento RZ F1

Arvento RZ characteristics

Resistance: HR: ToMV / Ff 1-5 / Fol:0,1 / For / On / Va / Wi

Harvested as loose tomatoes with a weight of 90 - 105 g.

Variety traits:

• High production
• Good flavour
• Long crop with a short fruit-bearing length
• Easy fruit set; the flowers are nice and quick
• Finishes its trusses nicely; tip fruits also set well
• Not susceptible to blossom end rot
• No hollow or angular fruit
• Firm tomatoes with a long shelf life
• Not very susceptible to botrytis
• The head does not grow away from the string; easy twisting

Tips for plant raisers

Propagation
Arvento RZ germinates quickly and easily and gives a nice, healthy plant. The truss usually appears at just the right height: the 9th - 11th leaf (not topped). It seems that in this phase, with a high light intensity, susceptibility to 'blind heads' increases in an Arvento crop.

Grafting
In principle it is not necessary to graft Arvento to give vigour. If there have been problems at the grower's nursery in the past with roots, root diseases or an extremely thin crop structure we would advise grafting, though.

Grafted, Arvento RZ comes into its own on a generative and vigorous rootstock like Emperador RZ or Stallone RZ.

Grafting always demands even more generative steering of the crop.


Tips for growers

Start of the crop

Temperatures

When giving temperature advice we realise that it should really be tailored advice in view of the many different growing systems. However, the advice given below can only be general advice.

Small plants:
For small plants we start the first few days with level temperature set points to let the plants get acclimatised to the glasshouse. Until a few days after planting we maintain temperatures of 19 - 20°C day and night, with a realised pipe temperature of at least 40°C.

From then on, and well before the first truss becomes visible, use a pre-midnight temperature decrease of at least 2°C. The idea is to quickly start working with generative set points.

The pre-midnight decrease of about 2°C has to be compensated for with a peak of 22 - 24°C in the afternoon. Arvento RZ quickly gives a strong head which can get a little large. Steer sufficiently generatively to prevent that the crop becomes too heavy.

Temperature advice for young/small plants:

• 24-hour temperature approx. 19 - 20°C, depending on the light
• pre-midnight 17 - 18°C
• night 18 - 19°C
• morning 18 - 19°C
• afternoon 24°C

Temperature advice for larger plants and/or when the truss becomes visible:

24-hour temperature of approx. 18 -19.5°C, depending on the amount of light.

If necessary, dare to take the 24-hour temperature as low as approx. 17 - 17.5°C for a short while if the light intensity is very low.
Lower 24-hour temperatures than 17°C will normally not be necessary in this crop phase.

Temperatures could then be:

• pre-midnight 16 - 17°C
• night 17 - 17.5°C +1 - 2°C increase on the lightsum; the heavier the crop, the greater the lightsum increase should be
• morning 17.5 - 18°C
• afternoon 24°C, with an increase for light of 2 - 3°C

Pipe temperature
Let the pipe temperature play a part in all the temperature set points above. There is no need for a min. pipe set point. Do aim for a realised pipe temperature of 40°C or higher, though, during this crop phase.

Although Arvento is not very susceptible to botrytis, susceptibility to it is determined to a significant degree during the first part of the cropping period.

Aim in particular to have the plants properly up to colour every day in the second part of the afternoon.

Achieve the afternoon increase shortly after midday and do not prolong it too far into the dark. Prevent totally exhausting the crop with high temperatures to avoid creating weak truss stems. Maintaining higher temperatures in the dark gives longer truss stems which are more susceptible to kinking.

Screens

Single, mobile screen:
For sufficiently generative steering, the screen should preferably be opened for at least a few hours every day. If it is not possible to achieve the target temperature it may be useful to keep the screen closed for once.

In order to get the crop nicely up to colour in the afternoon it may be useful to close the screen again during the course of the afternoon in order to realise the desired temperature. At this crop stage, too high a humidity does not play a part yet.

During the phase when a pre-midnight temperature decrease becomes important the screen can then be opened again for a short while in order to bring the plant temperature down quickly enough. Because there will be a loss of incoming light do not close the screen too quickly/early.

Fixed plastic screen:
Arvento is ideal for growing under a plastic screen, as it likes high afternoon temperatures. Use even greater day/night differentials under a plastic screen. Because the temperature is slower to drop in the afternoon when a plastic screen is in place, it is a good thing to go towards the night temperature set point a few hours before sundown. If the temperature is still reducing too slowly, ventilate above the screen. Don't be afraid, either, to also ventilate above the plastic screen as soon as the humidity is rising. And later still, slits can be made in the plastic to help expel moisture.

Double screen (combination of fixed plastic and mobile screen):
Arvento is also ideal for growing under a double screen. The advantage of this is that the desired temperatures are achieved more easily. This makes it even easier for the plant to find its balance.

Open the mobile screen every day when there is also a fixed plastic screen in place and do not close it until the late-afternoon temperature has dropped to the desired night temperature. See also under the above 'Fixed plastic screen' heading.

Watering and feeding
At this stage of the crop, watering also demands your attention. Do not give too little water but do remember that any water not given does not have to be used by the plant, either, by maintaining (high) temperatures. A set of scales is useful in determining the right amount of water to be given.

Saturate the slabs with 3.5 - 4.0 EC and give the plants 3.5 - 4.0 EC. From the time the plants have taken root in the slab go back to giving 3.0 - 3.5 EC. If the EC in the water is low, the EC in the slab will soon be on the low side.

From anchoring phase

On the slab
The plants should preferably not be placed in the planting holes straightaway, as this would increase the chance of getting heavy, more vegetative growth. When the first truss is fully flowering the plants can be placed on the slab. By not putting the plants immediately in the planting holes you also have more control over the nozzles, the plant will have more root tips to penetrate the slab and your heating costs will be lower.

Straight onto the slab
If you nevertheless choose to place the plants immediately in the planting holes it would be wise to saturate the slab with at least 4.0 EC and not to let the EC in the water drop below that value in the first few weeks. The slab should also already have been drained, and watering should be reduced to once every 2 - 3 days. Watering during the night also has a place here, so that the roots do not immediately absorb the water when given a watering round during the day and the crop does not become impossible to steer generatively. The type of substrate also determines this, of course. Our advice here is based on not putting the plants on the slab straightaway, because our temperature advice, too, relates to this.

Drying-out (for later plantings)
Once the plants are securely anchored, the slab may gradually be dried out from 80 - 85% to 60 - 65% moisture content. The guideline for this is 1% max. per 24 hours. Prevent too rapid and too much drying out. Be aware that there may be large differences in the moisture content of the substrate. Differences of 10% between slabs in one glasshouse block often occur and a moisture content of 55% is too dry, so keep an eye on especially the driest slabs (those near the gable ends, the centre path and in warm corners). Harmonise everything in line with the substrate used and the substrate volume!

Temperatures from going on the slab/the plants taking root in the slab
From the time the plants are placed on the slab there is a choice of growing methods, depending on whether you want speed or fruit size.

Growing for speed:
After placing the plants on the slab you can fairly quickly start using a brief pre-midnight temperature of about 16°C, a night of 17.5°C plus about 1.5°C on the lightsum, a morning of around 18°C and an afternoon temperature of 24°C +2 - 3°C, depending on the light.

Aim for a night temperature of at least 16.5°C. Use a day/night differential of at least 4°C.

For the greatest flowering and ripening speed it is important to maintain an adequate 24-hour temperature; depending on the light an average of 18.5 - 19.5°C. This prevents too high a fruit load around the first picking. The early and total productions will be high if you grow the crop like this.

By working with a lightsum increase on the night temperature you will automatically temporarily reduce the 24-hour temperature further when days are dark.

Growing for size:
Maintaining lower 24-hour temperatures than described above in order to grow larger tomatoes is also very well possible. It will give a slightly later early production and a high total production.

Steering sufficiently generatively with lower 24-hour temperatures demands even more skill.

When lower 24-hour temperatures are realised it is important to be very critical about the volume of water you give. When lower 24-hour temperatures are realised during this crop phase it is only too easy to overwater.

Head size
Adjust the 24-hour and afternoon temperatures to the amount of light. Always have some assimilates in reserve, but never too many. You may be guided in this by the stem thickness and darkness of colour in the head. A stem thickness of 10 - 11 mm with some purple colouration in the head is ideal. When the pH rises to more than 6 and the head size is more than 11 mm, the best thing is to increase the temperature. If the pH is less than 5.7 and the stem is thinner than 10 mm, decrease the temperature.


February to April

24-hour temperature
During this period the target temperature, when growing for speed, is usually somewhere between 17.5 and 19.5°C (if growing for maximum size: 17 - 18°C) with, as a guideline: 1,000 joules = a 24-hour temperature of 19°C. Always consider what is possible by letting it depend on the crop and the lightsum.

Low temperatures mean a longer maturing period and increasing fruit load during this crop phase as well. Do not let the crop become too heavy and vegetative during this crop phase. Too vegetative a crop beginning May will not be easy to steer generatively.

Arvento can cope with a bit of heat in these months as well. Its ability to recover is considerable. During this period, too, prevent that the crop is exhausted with high temperatures to produce the best trusses.

Aim for a day/night differential of at least 4°C. Realise this difference by maintaining sufficiently high day temperatures in particular. In the period around the first picking this day/night difference may temporarily be a little smaller.

Night temperature
In spring the pre-midnight in an Arvento crop may vary from 15 - 17°C, depending on outside conditions (radiation).

Always achieve the pre-midnight dip before the screen is closed. Gradually build up the night temperature again to 17.5 - 19°C min., depending on the lightsum.

When picking starts make sure that this temperature has been reached by 1.5 - 2.5 hours before sunup at the latest, in order to prevent that the tomatoes get wet from condensation.

If a higher 24-hour temperature is desired it is possible to increase the night temperature further in combination with a closed, mobile screen. This takes less energy than prolonging the day temperature and the crop remains stronger.

Morning dip
Later in spring it is often standard practice to briefly reduce the temperature set point around sunrise to 17 - 17.5°C, depending on the weather, in order to get strong trusses. If you want to use this morning dip, be aware of the following:
The crop can easily become too heavy and when it does, the leaves and especially the trusses can start to stick up more. This increases the risk of kinked trusses.

Do prevent too high spatial and pipe temperatures shortly after sunup. This may be achieved by having a lower limit for the max. pipe during this period; it will keep the crop and truss stems shorter and stronger.

Fixed plastic screen and moisture
Most of the time a fixed plastic screen will be removed at the start of this crop phase. If it is still in place, beware of too lush growth and botrytis susceptibility!

Leaving the fixed plastic in place will require even greater day/night differentials than you were used to using before. Have the night temperature set point sufficiently low and compensate for this during the day with higher temperatures. This will also increase the moisture deficit during the daytime.
If moisture is a problem then ventilate above the plastic. Also having slits in the plastic will expel a lot of moisture. Be more careful with watering than you would be with a mobile screen.

Ventilating
Do not allow cold air to enter the glasshouse when ventilating around sunup and in the early morning. Limit the ventilation gap during this period if outside temperatures are lower than 17°C. Too much ventilating towards morning and in the morning (without a closed screen) results in tough and short leaves and increases the risk of pale leaf edges and/or yellow heads.

Afternoon
During the course of the morning the temperature may be allowed to rise gradually, and in the afternoon a temperature of at least 22 - 23°C is desirable at all times. If there is plenty of light you can increase the temperature further and possibly prolong it slightly. If the weather is dark, the temperature has to be reduced to the night temperature set point after only a few hours and in this case, too, it should not be prolonged till after sundown.

During this crop phase do not or hardly ventilate on the windward side during the course of the afternoon.

Preventing stick trusses
Arvento will give stick trusses especially when the crop becomes too heavy and the trusses start to stand up. They will then only kink at quite a late stage so that the fruit weight and the truss will still be adequate. By steering sufficiently generatively and aiming for a crop that is not too heavy, this can mostly be prevented.

Another cause of stick trusses is too dense a crop, so remove small leaves from the head and do not have too high a stem density. Both are discussed later in this manual.

Removing small leaves
Arvento needs an open crop structure at all times. From the moment you retain the extra stem take a small leaf out of the head; preferably the leaf above the flowering turss. In most cases it is advisable to take a leaf out of the head on a weekly basis. This keeps the crop more open, which keeps the truss stems stronger and the truss weight will be higher and more uniform.

A less dense crop also needs less heat and that saves energy.

During the summer period (June/July) it may be useful not to take any leaves out of the head for a time. Start it again by 1 August at the latest. If the crop looks fairly heavy, continue taking leaves out of the head in the summer period as well.

Growth pipe
The growth pipe (if present) may be used as the primary heating method from the 4th/5th truss if it is located below the first truss. From two weeks before the first picking we like to see the growth pipe just below the truss to be harvested; the maturing time of the tomatoes can be steered better that way.

By using the growth pipe more from now on, the heat is used more effectively. In contrast with the lower heating network, it is easier to increase the temperature of this pipe without it costing extra in gas, raising the spatial temperature too much or expelling heat unnecessarily via the vents. Moreover, there is a lower risk that the vents are opened too far because of higher temperatures and there is less cold air coming in because the vent position is lower.

The growth pipe is also very effective in preventing botrytis, especially when you start de-leafing! By temporarily increasing the pipe temperature after de-leafing by breaking or cutting, the wounds will dry faster.


Summer

Temperatures
Virtually all summer, too, the target for the night temperature is 16.5 - 17°C. Achieve this by having the pre-midnight set point sufficiently low, 14 - 15°C, when outside temperatures are higher. Follow this with a gradual increase to 17.5 - 18°C for the night temperature and aim to have reached this 2 - 3 hours before sunup. This will prevent that the (large) tomatoes get wet with condensation.

True summery conditions require that the 24-hour temperature be reduced but if conditions are less summery do not grow the crop too cool. Too low realised night temperatures can result in too large tomatoes which become more susceptible to russeting. During cool summer periods the 24-hour temperature should always remain above 18.5°C. Too low 24-hour temperatures will very quickly give a heavier and more vegetative crop that will be more difficult to steer in autumn, resulting in stick trusses later on.

Ventilating
Towards the end of the morning it is advisable to see whether the vents on the windward side can be lowered a little. During drying weather it is best to gradually lower the vents more and more. Do not start this too late in the afternoon.

In the summer, too, it is good on cooler days to realise a higher 24-hour temperature by means of an afternoon peak. This can usually be realised by keeping the vent position lower in the afternoon. It also means that more CO2 will remain available to the plant and the plant will continue to grow better, in spite of increased generativity, because of a less drying climate. It certainly gives a higher fruit weight.

CO2
Arvento likes a lot of CO2. When the glasshouse temperature in summer is higher than the outside temperature, we would advise to take a good look at the CO2 dosing.

Late summer/autumn

Arvento will fairly easily start making more crop mass in late summer. Steering generatively in order to prevent a heavy, vegetative, dense crop is very important in late summer/autumn as well. In a heavier, more vegetative and/or denser crop the trusses will stick up more again and kink earlier.

In this period, too, it is true that striving for lower 24-hour temperatures will give a heavier, more vegetative crop more rapidly.

Prevent too dense a crop by keeping the number of leaves in this period at 12 - 15. From beginning August at the earliest it is best to start picking leaves out of the head again. Later on in autumn you can also take leaves away at the front of the plants.

A more open crop in autumn gives the highest average fruit weight for Arvento.


Watering, EC and feed

Arvento needs a high enough water-EC in order not to let the EC in the slab drop too low. In spring we add 3.0 - 3.5 EC; in summer this is 2.8 - 3.2, depending on the EC in the slab/run-off. During the summer period, decreases for light at midday are usueful. Do not exaggerate this decrease for light - 0.4 is sufficient. Always strive for an EC in the slab of 4.0 min. and 5.0 max..

Make sure that enough fresh feed is always offered. If circulating, we advise to always give the plant at least 2/3 fresh water and feed.

Starting watering too early causes more 'stretch' in the trusses. It is better to let the crop start transpiring before starting the watering rounds. Growing generatively also means not starting too early with the watering in the morning during the first crop phase. If you do, the colour tends to be lighter for the greater part of the day. That would mean too extreme prolonging of the afternoon temperature, resulting in weak truss development.

A little bit further into the cropping period we like to start watering in good time in the morning and stop in good time, i.e. not too late, in the afternoon.

Potassium:
Arvento requires a lot of potassium. Adjust the amount of potassium sufficiently when the third truss is flowering. From then on the analysis values determine the absolute amount. Aim for a value of 7 - 8 in the substrate. Too low potassium values increase the chance of PepMV symptoms.

Calcium:
From April onwards, increasing the amount of calcium is vital. Always, incidentally, aim for a calcium value in the substrate of at least 10. From May, 11 or 12 in the slab is ideal.

Sulphate:
These days, low sulphate values are often the aim. However, the sulphate value in the substrate should always be at least 4.5. This is positive for colouring of the tomatoes and fewer PepMV symptoms.

Ammonium (rival of Calcium):
The amount of ammonium should be adjusted to the pH and the amount of water given. This means in general that in spring you will be able to follow the standard, recommended values. If you give more than 4 litres water/m²/day, reduce the amount of ammonium. If using solid fertilisers it is usually necessary to replace part of the solid nitrate of lime with liquid nitrate of lime.

Trace elements:
Arvento demands generous amounts of iron and manganese.

pH:
Because of its vigour, the pH can rise quite easily. Ensure that it does not remain at much more than 6.0 for too long.

Sufficient water
Due to its vigour, the crop type and high production, Arvento has a high water requirement. This means that between 11.00 am and 2.00 pm generous watering rounds are virtually always required. Make sure you make water available frequently enough, especially from April - beginning July. In extreme circumstances our advice is to give at least 4 cc/joule/hour.
As well as giving plenty of water make sure that there is also enough oxygen in the slab during the late afternoon, evening and night. High volumes of water make good drainage of the substrate essential. Reduce the run-off percentage considerably between 2.00 pm and 3.00 pm (depending on the weather), so that you have hardly any run-off from the last watering round(s).

In spite of the high water requirement, do not continue watering too late in the afternoon or evening. The substrate also has to dry out in summer by 6% (more than 1,500 joules) to 10% (less than 1,500 joules) between the stopping and starting times. The same applies to substrates other than rockwool but exact percentages and times may differ.

Wet substrates will need extra drainage holes after 1 July in order to get enough fresh water in the slab.

False run-off
It can happen that the water is more or less forced through the slab or enters and exits the slab too quickly. This will be the case sooner if the output/minute/nozzle is quite high and false run-off will occur very quickly. Larger watering rounds and smaller substrate volumes, drier substrates and nozzles near the drainage hole will compound the problem.
The plant must still be able to absorb enough water but in such situations it is a common mistake to think that "there is enough run-off, so the plant must be getting enough water". In that case even more run-off is required in order to enable the plant to absorb enough water. If attempts are then made to reduce the run-off percentage in the middle of the day by watering less frequently, the plant will be unable to absorb enough water at extreme moments. This is at the expense of growth, fruit weight and production.

From mid-July onwards it is important to steer a little more generatively again. It is often useful from now on to let the slab dry out by 10 -12% between stopping and starting times. This may be realised by stopping slightly earlier.

The exact watering strategy should always be assessed per nursery situation.



Truss treatment, truss pruning, plant distance and extra stems

Truss treatment
In Arvento crops, truss treatment should be carried out from the first to the 7th/8th truss and is usually continued for as long as work allows (i.e. up to the start of harvesting). What method is used often depends on the region but in connection with hygiene and convenience it will usually be bracing. The truss stems are also ideal for scratching/pinching, but this requires more skilled personnel.

The result of truss treatment is that the fruits mature faster and better. This takes the fruit load very quickly to a satisfactorily high level so that the fruit ensures that the plant finds its balance sooner. The higher you have the temperature, the longer you will have to brace the trusses (especially if the heads are close). If in doubt, brace an extra truss.

A number of growers get positive results from bracing the last three trusses. Pruning the first 2 trusses at 6 is advisable for early sowing dates.


Plant distance and extra stems
Arvento certainly does not demand a high stem density. It needs plenty of light and air to give a good yield. High stem densities in an Arvento crop are only detrimental to production and have a negative effect on the good quality (lower fruit weight and lesser fruit shape). Depending on glasshouse type and the amount of CO2 available we recommend a stem distance of 36 - 37.5 cm in summer. In practice this means that no more than 3.3 - 3.5 stems/m² should be retained.

Arvento does not always give a good extra sideshoot so easily.

Plant distance 50 cm:
The initial distance in light glasshouses is preferably 50 cm, reducing to approx. 37.5 cm some time during weeks 8 - 11.

Plant distance 66 - 75 cm:
Double the number of stems at truss 2 or 3 (planted before 15 January). In crops planted after 15 January the first truss sideshoot may be retained. In that case, regularly take an extra small leaf out of the head from the start. It is very important with this stem system to keep the crop open because the final stem distance is reached quite early on.

De-leafing: breaking or cutting?

We cannot give clear-cut advice on this. Both are used in practice with good results. It is important that no butts are left behind. Some growers only cut the leaves in those weeks when the leaves are more tightly attached to the plants, others prefer to cut leaves year-round. Although Arvento is not very susceptible to botrytis, working less hygienically and/or less accurately does increase the risk of botrytis. Now that all growers are - of necessity - trying to use less gas this is even more important.


Summary

• Arvento RZ demands generative steering
• Realise day/night differentials of at least 4°C
• Keeping the crop open is a must
• No need for high stem densities
• Provide sufficient water and feed

Crop advice given by the seller is not binding. Descriptions and recommendations in this manual are as accurately as possible based on experiences in trials and practice. We cannot, 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 this manual is suitable for the crop envisaged and/or local conditions.