Technical Information
Malling Centenary Plant Propagation Guidelines - November 2017

These fruit production guidelines for Malling Centenary are based on Jorrit de Vries’ agronomic observations and trials work for Meiosis Ltd.

 

The two main challenges for the successful production of Malling Centenary are disease control (especially Phytophthora cactorum and Pestalotiopsis clavispora) and ensuring sufficient flower truss initiation to provide economic yield.

 

Malling Centenary is known to be susceptible to Phytophthora cactorum. In commercial production Pestalotiopsis clavispora has also been identified in plant samples. This disease is not well known in the UK and northern Europe, but a useful summary of disease characteristics and potential control measures can be found here.

 

The symptoms of both diseases are similar, and it is possible that P. clavispora weakens the plant then P. cactorum lethally infects the plant.

 

Management of fruiting plants needs to minimise the conditions that enable both pathogens to infect the plants:

      • Ensure adequate nutrition to maximise plant health
      • Minimise irrigation
      • Ensure very good drainage of water away from the plants
      • Minimise physical damage to the plants so there are no points of entry for diseases
      • Control insects, especially sciarid fly, that can cause physical damage to stems

Nutrition

      • Optimum nutrition is necessary to reduce plant susceptibility to fungal disease.
      • To achieve healthy plants with good truss numbers plants should be propagated very generatively from the beginning.
      • It is also suggested, though hasn't been put into practice prior to Autumn 2017, that maintaining feeding right up until cold storage may help to reduce disease susceptibility.

 

Current recommendation for feeding:
Propagation recipe

Ammonium        0.0 millimoles
Potassium        5.0
Calcium        6.0
Magnesium        1.0
Nitrogen        11.5  
Sulphate        1.5 
Phosphate       1.0
Iron        30.0 micromoles
Manganese        20.0 
Zinc       7.0
Boron        15.0
Copper        0.75
Molybdenum        0.5

 

NB The elements in the same ratio as for fruiting mix.

 

 

NITROGEN:

      • Trials at Proefcentrum Hoogstraten (PCH) have demonstrated that relatively high levels of feed in tray plant propagation can reduce plant losses due to disease and increase flower initiation giving increased yields.
      • In PCH trials, Nitrogen was applied in the form of Calcium Nitrate; it could be that the higher level of calcium was a key factor.
      • It is recommended that very low Nitrogen is required in propagation with higher levels of Calcium to keep the plants generative.

 

CALCIUM

      • Malling Centenary can be affected by tip burn due to low calcium levels in the plant, and this can be severe enough to cause the loss of the first fruit truss.
      • Therefore, measures must be taken to ensure maximum Calcium levels in the plant during and especially at the completion of the propagation cycle, when plants are being taken into cold storage.
      • This can be achieved through the use of foliar feeds containing Calcium. Calcium Chloride (for example Koppert Veni Calcium) has been shown to supply Calcium in a form that is easily available to plants, helping to quickly correct localised deficiencies.
      • Calcium is an important element. In propagation apply Calcium six weeks prior to packing, or during the whole propagation period. Maximum Ca level is not known.

Irrigation

      • Malling Centenary requires less irrigation than other varieties such as Elsanta.
      • Overhead watering will encourage disease therefore irrigation needs to be managed carefully in propagation and fruiting plants.
      • Apply more water in each application, but at less frequent intervals, though overall water application is less than for Elsanta.
      • The less frequent watering events minimises the fluctuations in substrate temperature, and a uniformly stable temperature stresses the plant less.
      • Malling Centenary is sensitive to less than ideal conditions.
      • To achieve optimum irrigation, planting tips together that are at the same growth stage aids water management.
      • In the tray plant propagation field, the tips should be carefully size graded to ensure the resulting plants have similar water requirements; this will help avoid over-watering smaller plants that are being grown in the same field as larger tray plants.

 

EC levels

      • In tray plant propagation after establishment of the roots aim for an EC of 2.0–2.5 in the substrate.
      • Maintain EC levels in substrate hanging tip production drip water at 3.0-4.0

 

Growing media

      • A freely draining media is recommended such as coir.

 

Tray Production

      • Striking tips in small modules before transplanting to full size trays can encourage more generative growth rather than vegetative growth
      • Flower initiation is stimulated earlier resulting in a longer period for initiation to occur which gives the potential for more trusses.
      • Indoor tray plant production can result in late initiation.
      • Transplanting should occur when the roots are well developed.
      • Start to apply fertiliser 10 to 14 days after striking.
      • Apply Fenomenal and Paraat according to manufacturer’s instructions and conditions of approval.

Tip Production

      • One of the key factors required to produce strong tips is high light levels with stable temperatures.
      • Pre-flowering has been noted on the first tips produced by micro propagated mother plants in hanging tip production.
      • Development of pre-flowering tips is being followed through to harvest in 2018; tips cut for tray plant production have so far developed as normal.
      • Cut tips store well at low temperatures (2°C) and high humidity for a number of weeks

Tipping dates

      • Cutting date of tips is not thought to be crucial though the propagation of a large plant with the maximum number of flower trusses requires as long a growing season as possible.
      • Although every growing season is different, it would usually be best to ‘tip’ runners and plant into trays by the start of July.

 

Cold Storage

      • It is suggested that feeding the plant right up to the point of cold storage may help to reduce disease susceptibility, though this has not been trialled prior to Autumn 2017.
      • Ensure all elements have been translocated into the root before cold storage (measure sugar levels in the leaf and the upper root zone).
      • Thoroughly inspect plants prior to cold storage
      • Separate and/or grade-out any plants that have weak root development and/or are showing symptoms of dieback in order to reduce/limit losses in fruiting crops.

Chemical use

      • Any chemical use should always comply with the regulations in the country of use, if in doubt seek professional advice.
      • Fenomenal is effective against both P.cactorum and P. clavispora; Paraat is effective against P.cactorum.
      • In tip propagation the most effective way to apply Fenomenal is as a 15-minute drench to the tips post cutting, pre-cold storage or planting
      • The use of Folicur is not approved or recommended with Malling Centenary as it can significantly reduce the leaf petiole and truss length.

Plant type

      • Several propagators have tried techniques to produce larger healthier plants, such as establishing tray plants or waiting bed plants from cold-stored ‘frigo’ plants rather than ‘tips’ or fresh field-grown runners
      • Establishing ‘tips’ as misted-tip modules before potting on into trays is another possibility
      • Double cold stored plants can show more variability in truss numbers due to later plant development and therefore initiation
      • Tarsonemid mite control is crucial for double cold stored plants.#
      • Generally, bare-root plants have shown less disease susceptibility than tray plants. Focusing on smaller ‘A’ grade plants at higher density plantings (30/m) has given good results in fruiting.
 

Flower Mapping

      • Variability between flower mapping and actual fruit production has been high in some instances.
      • Although no work has been funded, commercial laboratories are developing their methods to provide a more accurate assessment of the truss and flower numbers present in Malling Centenary

TRIALS AND COMMERCIAL PRODUCTION OBSERVATIONS

Glasshouse early planted Planting date: 12/01/17 First harvest: 20/03/17

Waiting bed had more flowers but developed slowly Tray plants produced large fruit but had 20% plant losses No second flush

Very high picking speeds achieved – 85kg per hour Production too low for all plant types.

Glasshouse over-wintered crop Planting date: August 2016 Autumn crop taken

Over-wintered at 10°C, no chill

Reacted very well to night-break lighting Very good spring production

Flowered until the end of July

Table top early planting

Waiting bed needed one more truss

Tray plants didn’t develop as normal due to Folicur (tebuconazole) use in propagation – severely shortens leaf height and truss length.

Poly-house fruiting of ‘A’ grade bare-root plants – 60-day substrate production

Planting density: 30 per metre No plant losses

1.5 trusses per plant on average

5 berries per truss = 225 berries per metre 20-30g per berry

99% class 1 + high picking speeds

Compares favourably in production to other tray plants where plant losses can be an issue.

Glasshouse fruiting of ‘A’ grade plants – double cropping

Planting date: 28/08/17 First harvest: 21/10/17 Plant density: 30 per metre

Picked biggest yield in November – results to follow for autumn 2017 crop & spring 2018 crop

Meiosis Ltd seeks to make it clear that the information contained above is based on practical observations but not on robust replicated trials. No warranty is given or implied and, to the maximum extent permitted by law, Meiosis accepts no liability for loss, damage or injury howsoever caused (including that caused by negligence) or suffered directly or indirectly in relation to information and opinions contained in or omitted from this article.