Is there an alternative to MKP for soft fruit growers?

Monopotassium phosphate, otherwise known as MKP is a product synonymous with fruit production that is widely used, primarily as a flower boosting green fruit supporter. However, at this point in time, MKP is difficult to get hold of, so many growers are asking if there is a suitable alternative.

The reason behind the shortage lies with international politics. Last month the EU imposed sanctions on Belarus following the interception and forced landing of an international flight followed by the arrest of a prominent journalist and anti-government critic. So what does this have to do with UK fruit? A little known fact is that Belarus is a major global supplier of raw mineral phosphorus fertiliser grade minerals, so with EU sanctions and potentially a USA embargo, supplies of commodities out of Belarus are looking quite tight. There is a restriction in supply, meaning an increase in demand and a subsequent increase in prices. All of which have a knock-on effect further downstream on phosphorus heavy fertilisers, like MKP. This disturbance in the supply chain has caused a global reduction in supply and price increase ex Belarus, followed by consequent phosphorus fertiliser price increases in general.

Yara previously supplied monopotassium phosphate as YaraTera Krista MKP, however, due to the problems with supply, this is no longer easy to get hold of and an alternative is needed.  So, what can we do?

Fortunately, there are other options. Although monopotassium phosphate has been widely used historically in UK fruit, much has changed in fruit production since MKP was first introduced and even if it were still available it might not be the best choice.  Instead, we would recommend you take a look at integrating the Yara Kristalon range into the current fertigation program as an alternative for the less available and becoming more expensive MKP, for the following reasons. Specifically, we recommend YaraTera Kristalon Brown, although YaraTera Kristalon Scarlet is also a good alternative.

Using Kristalon Brown in place of MKP is not solely about the lack of phosphorus. Kristalon Brown also contains all of the micronutrients and a low percentage of nitrogen too, which means it can be integrated into an existing program and keep the new program in balance. Kristalon Scarlet can do the same, but Kristalon Brown is lower in N at just 3%.

Krista MKP was all about supporting the flowers and green fruit as a primary use, with phosphate also for supporting the roots in bag production. Kristalon Brown by contrast has less phosphate than MKP and a higher ratio of potassium, so to use it well the fertigation programme will need to be adjusted slightly, although there are a few trade-offs in the thinking. Kristalon Brown is a great flower and early fruit supporter in its own right as good as MKP and also free from chlorine which makes managing EC far easier.

The main difference is there will be less phosphate for root growth and the plants will need to work harder. However, much of the MKP debate is historic and based on older varieties like Elsanta and Sonata. Strawberry and indeed raspberry/blackberry varieties have changed significantly since MKP was first introduced. The new verities are more vigorous and expected to work harder in the rooting zone so this is an option now, whereas in the past it was not. Also, there are other inputs that can be introduced to the rooting zone, such as YaraVita Actisil and or YaraVita Biotrac which will help the root mass develop and grow stronger in the absence of MKP. Kristalon Brown has a full complement of micronutrients available and only 3% N, where MKP has nothing in micros. This means that Kristalon Brown is a more precise formulation designed to give exactly what the plant requires. Where MKP is purely about macro inputs. With the inclusion of these micros, thinking about using Kristalon Brown brings more advantages to overall crop health as a fuller product than had been the case with MKP.

Whilst Yara Kristalon Brown is a good alternative to YaraKrista MKP it is actually a much more complete product with several advantages over the traditional MKP. This used to be reflected in the price, however with the change in the supply situation this is no longer the case and now we see a comparative pricing structure between the Kristalon range and Krista MKP based largely on phosphate content which negates any price difference between the two products and may on some days lend Kristalon Brown in favour over Krista MKP. Kristalon Brown is a more widely used product globally, which means it is more readily available than Yara Krista MKP. Yara Kristalon Brown (and Scarlet) are available at the moment with forward supplies looking good.

To sum up, if your supplies of Yara MKP are looking tight, Yara would recommend a shift into Yara Kristalon Brown which can achieve similar or better results than Yara Krista MKP. While the Phos issues are resolved, though once you try Kristalon, you may find Brown’s ability to boost the flowers and promote overall crop health, a far better solution than using MKP plus other singles.

Managing strawberries under higher temperatures

At last, summer has arrived, UK expects ambient temperatures of plus 24 deg C, this means that tunnel temps could well climb over 28 deg C at the peak of the day. For strawberry growers, this is both good and bad news at the same time. The news is that BBQ weather is coming, the UK is on a tentative full unlock setting and many people up and down the country are enjoying what freedoms have been given back. All the more reason to celebrate with some UK grown strawberries and cream.

The downside is high heat brings with it challenges for UK growers. Strawberries are temperate crops and can enter thermal dormancy after growing temperatures exceed 28C. Strawberry crops at thermal dormancy continue to grow vegetatively but lose the ability to flower, even if there are flower buds in the crown.

This means that growers should look to vent tunnels in order to keep strawberry cooler than 28 deg C through the peak of the day. Fertigation may need to be increased in frequency so that watering can keep the roots cool. Doing this however will increase the runoff from 12% closer to 22% and should the ambient heat disappear care should be taken to reverse the system, not to overwater. This can be best achieved by keeping a steady record of the water runoff, sampling for its content, measuring the bag E.C. and crop walking.

Controlling the crop through these tricky periods can be made easier by utilising foliar feeds. Varieties such as Sonata become soft under high summer heat days, this softness can be mitigated by using YaraVita STOPIT to help firm up fruit structural cells while combining with YaraVita ACTISIL to further strengthen fruit skin density. The two applications help varieties with medium berry strength to gain better storage and shelf life.   

The rapid changing temperatures from high heat during the day to cooler weather at night can present some significant fluctuations. Strawberry crops under fruiting are at a time when the crops load is significant and are very susceptible to stress. YaraVita BIOTRAC has been specifically formulated to support cell multiplication, ideal for strawberry during the green berry stage. YaraVita BIOTRAC has the ability to further mitigate both heat and cool stress, owing to its two key enzymes taken from Ascophyllum nodosum. YaraVita BIOTRAC would be an ideal foliar product to use on all soft fruit as they navigate this tricky hot/cold period, buffering the stress caused by temperature fluctuations.

With high heat and humidity after such a wet period in May, the risk of Mildew and even Botrytis will be very high. YaraVita SENIPHOS is an old favourite for changing leaf zone microclimates to less favourable conditions for these fungi to make a big impact on the crop. Again combined with a YaraVita ACTISIL application to further suppress the opportunity for Zoo spores to spread. These products should not be used in isolation but as a part of an existing fungicide program.

Concern about hail damage to apples and pears

Apples and pears have both seen some unseasonal weather recently with some very late hail showers that have damaged crops and caused concerns for growers.

Pear orchards in the southeast were worst hit with late hail showers, with the primary concern surrounding the mechanical damage to the leaf. A few of the more exposed fields looked quite battered immediately after they happened. Now two to three weeks on growers are using products like YaraVita BIOTRAC to nurture damaged leaf back and considering products like YaraVita ACTISIL for increasing skin strength on the back of weakened fruit skin. Most pear growers are fortunate as at this stage of development, pear fruitlets are pointing up vertically. The pear crops do this naturally, with the weight of the fruit pulling them down as they fill. With the majority of the crop being vertical pear fruits, even in exposed areas, many have evaded the worst of the hail, however, the leaves being more horizontal have taken the brunt of the damage. Assuming growers can see good leaf recovery, then there is still a good chance that these pear crops will retain their fruit come fruit fall.

Apple orchards, particularly Cox and Bramley were also hit by some very late hail showers, with damage of up to 40% in Cox and 25% in Bramley being reported. Apples unlike pears have seen some damage to the fruit lets, small though they are. The concern now moves to how these fruits will develop, fruit fall is the next event coming. Post fruit-fall if there is an opportunity some of the more damaged fruits can be removed so crops can be grown through the damage. Where leaf damage is a concern, YaraVita BIOTRAC followed by YaraVita CROPLIFT PRO is a good option for recovery.

Two to there weeks later on apple crops continue to be stressed, with many orchards beginning to recover and growers reporting that new leaf buds have begun to produce new leaflets. However, there is still a need to remain vigilant as the extra growth requirement as a result of this stress may have repercussions for good wood development later in the year so for some of these earlier varieties, YaraVita BUD BUILDER may need to be considered later in the season to build back strength into woody growth and help develop next season's buds.

Recovering from frost damage to apples, pears and grapes

In 2021 the weather was very different from just about every other year of our 5-year average. Similar to the previous year we had early heat in late February lasting no more than two weeks. Enough time for the early varieties to begin, signs of bud swell, however, a dry April ensued and temperatures began to plummet, come late April despite bud swell and first true leaves emerging, temperatures of -6 deg C were recorded on a few nights, though the average minimum temps were on average around -1 deg C. This early heat and late frost have led to some varieties losing not only young vegetative growth but entire buds that had been chilled right back. Now the frosts have largely past we need to think about managing the crop buds which are left. Yara’s solution to this problem is to use two products with very specific targets.

YaraVita BIOTRAC is a biological stimulant product combined with a micronutrient formulation of potassium, boron and zinc. The biological component of YaraVita Biotrac consists of two key enzyme’s extracted from Ascophyllum nodosum. This extraction allows YaraVita Biotrac to be more concentrated than other similar seaweed formulations which allows a lower application rate for the same benefit.  The Ascophyllum nodosum enzymes nurture damaged vegetative matter, helping the plants with new cell division as they recover the growth and coating any softer tissues reducing the impact of secondary infection sites. The Nitrogen component of YaraVita Biotrac is a component of the Ascophyllum nodosum enzymes. The potassium, boron and zinc in the formulation aid young bud development.

YaraVita CROPLIFT PRO is an old faithful and well known in all crops. It is a complete balance of NPK & micronutrient foliar feed, which delivers a perfect balance to the new growth to bring the crop on to the level the growers would have expected from an unfrosted crop.YaraVita Croplift Pro will recover much of the lost growth without having too high an NPK balance as to create extra vegetative growth later which would require more pruning.

Fruit agronomy advice

An eye on next season's second year woody fruit crops 

Post fruiting plants dedicate much of the later part of the year to bud development for the following years crop so good late season nutrition is vital for next season's crops.

YaraVita BUD BUILDER FL a wettable powder, was developed with the grower base to perform exactly this task. Feeding the developing new buds and surrounding leaves, with good mixture of Phosphorus, Magnesium, Boron and Zinc. These key minerals are required for making good and strong buds. It is important to get as much feed into the plant buds at the end of the year as it is difficult to feed the buds in the start of the following year, without running the risk of waking them up early. Feeding dormant plants has always held the risk of starting them from the winter sleep. The key issue being that once the plants have started though they can slow in growth, they can’t go backwards. This means a late frost can badly damage early waking plants, as happened earlier this year with the grape crop that were woken by early heat in February.

Once buds have woken in Spring YaraVita BUD BUILDER FL can be applied again as it continues to help the plant bud opening and early development.

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Tired looking late season fruiting crops may need a foliar feed

Some of the more productive late season fruiting crops can look tired as they run through the last part of fruiting. Having translocated much of the internal nutrients to fruit production there may be little left for maintaining leaf at the end of the year. Weak plants which are planned to be taken over tend to struggle in the following years main crop as they start the year low on energy.

A simple solution for these crops is to consider using YaraVita CROPLIFT PRO a broad spectrum foliar feed containing a good balance of NPK to give an immediate boost to tired leaves. YaraVita CROPLIFT PRO as a foliar feed will not impact overall N calculations. As a targeted leaf feed it is further unlikely to change the flavour of the remaining berries as they come ripe for picking. A macro N input should be avoided at this point in time as the strawberry crop is expected to enter dormancy in autumn. With a dose of macro N its likely the plant will be too vegetative to begin the dormancy process and would most likely be damaged by November frosts. For this reason YaraVita CROPLIFT PRO offers the best solution for maintaining final strawberry harvests while boosting plant health just prior to dormancy at the end of the year.

End of season soil sample on kept strawberry crops

The end of the season is fast approaching, there is a significant benefit to planning an end of season soil or substrate analysis. This should be considered as it offers the grower two separate opportunities to understand what is going on in the bag.

Firstly, when this result is compared to the earlier soil and leaf analysis, the fertigation manager can see what nutrients have been used up by the crop and what nutrients may still be left within the bag. This would allow for fine-tuning of the following year's ratio’s to limit next years build up. Secondly, the information when combined with next year’s start test, will allow the grower to see what has happened over the winter period. Though plants remain dormant, the bags are often watered by the weather and an element of residual salts and minerals may be washed out of the bag. Combining this to the following years fertigation allows the grower the opportunity to aim to start the main crop year with as close to a clean bag as possible.

Late season soil or substrate analysis can be made with Yara Analytical Services.

The importance of iron application late summer-early autumn strawberries

Strawberry production will be in the final parts of picking at this time. Iron deficiency can normally be observed at this time on the leaf as the plant is giving most of its resources to fruit production. Iron deficiency takes time. In severe cases a foliar feed like YaraVita FERLEAF 100 can be applied to relieve the situation. For crops that will be kept through the winter and given the reduction in NPK inputs late summer into early autumn is good timing to fertigate iron into both the bag and plant as they grow down into winter. Filling the strawberry plants with Iron now like YaraTera Rexolin Q15 a chelated product releases the need to do so in the early part of next year when the fertigation can concentrate on nitrogen and low PK inputs through an A/B system without the complication of iron in the system.

Foliar micronutrients reduce crop stress

Wet years bring an increased likelihood of softer leafy growth. More nitrogen less calcium tends to increase this situation, to the benefit of sap drinking insects like an aphid. Aphids take advantage of the soft cell walls piercing the leaf with the proboscis and extracting the sap. Stronger leaf resists aphids better, in a normal year the aphid would be seen on the newly emerging leaf as they are much softer. Maintaining a good micronutrient regime on crops can limit the impacts of softer growth leading to decreased pest pressure.

As the weather is set to warm up from a saturated soil condition, this year will become as last year, ideal for fungal growth. Fungal pathogens are much harder than anaerobic soil conditions, needing only warmer temperatures to begin their cycle. The plant site of infection roots, crows and lower stem will be softer in spring due to saturated soil. Combine this with softer leafy growth higher up and the fungal pathogens can land anywhere and have an impact. Expect mildew (downy more than powdery), botrytis and phytophthora (root rot) to be issues this year. The key to these is good husbandry and trying to break up the micro-climate which these pathogens love. Foliar feeds like YaraVita SENIPHOS and YaraVita THIOTRAC 300 can further help to keep suppressing fungal pathogens by breaking the microclimate at leaf & fruit level while maintaining nutrient uptake. Foliar feeding reduces the demand on the roots reliving root stress as soil conditions return to a more normal state. As the roots need to get back to better root condition, feeding foliar YaraVita BIOTRAC can help reduce plant stress while at the same time adding root stimulation growth from the organic plant enzymes contained within YaraVita BIOTRAC.

The benefit of foliar fed calcium in wet years

After a wet winter, with heavy rainfall following flooding from last autumn, both soil and many pots grown fruit plants have been under saturated conditions for all the winter. The three-week forecast for the UK moving forward is less rainfall than previous years but some rain is still expected and the start of the season is looking dry and slightly windier than normal. Given the weather outlook, the application of foliar fed calcium would be advantageous.

In grape and cherry crops in a high-water year, fruit issues are seen with ‘splitting’ in the fruit after fruit swell pre full ripening. This issue in both crops is caused by the same physiological condition of too much water uptake and lack of calcium uptake. Calcium is a key nutrient for strong leaf and fruit growth, its key component of cell walls.

Calcium is an immobile nutrient and is difficult for roots to take up under saturated conditions, as highly mobile nutrients are far more available to root. Further, soil microbes that would normally aid the breakdown of calcium for root uptake perform badly in saturated water due to lack of oxygen. Given the lack of uptake of calcium from root level in wet years, building and keeping good leaves is essential. The leaf can in a wet year provides both functions of photosynthesis and nutrient uptake from foliar feeding of immobile nutrients like calcium. It is important to remember that the leaf must be free from deposits if it is to continue with good photosynthesis. Building up calcium in the leaf will limit the ability of the leaf to perform its primary function. Therefore, the efficacy of the calcium feed used must be correctly formulated for an even spread. This is particularly important in wet years when plants can succumb to stress more easily.

As discussed above, this year crops will need a foliar application to support nutrient uptake reliving root pressure. The coverage of leaf needed to be uniform to aid efficacy and more importantly reduce deposits building up, blocking photosynthesis. All YaraVita foliar feeds are tested and formulated thoroughly to make sure they perform through the application machinery and upon contact with leaf spread uniformly, with no build-up. This has been demonstrated in on cherry using the Yara foliar feed of YaraVita STOPIT.

Apple fertiliser and crop nutrition advice
Apple fertiliser and crop nutrition advice

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