Managing cropping schedules and harvest quality in brassica crops is heavily dependent on the crop’s response to inputs under different growing conditions and stress factors. We take a look at how the relatively simple addition of foliar supplements can deliver significant benefits in plant stress management.

Crop nutrition has traditionally focused on the timely supply of fertiliser minerals to prevent nutritional stress but the use of foliar phosphites and biostimulants to support the 3 R’s of plant stress management – rooting, resilience and recovery – can also give growers more options to counter less controllable factors such as weather, pests and disease and crucially, help achieve more uniform growth.


The size and health of brassica roots are vitally important to producing healthy, vigorous crops. Strengthening root architecture will improve their access to soil-held nutrients leading to stronger, more consistent growth and ultimately crops that are better equipped to withstand adverse conditions.

We have two main nutrition tools for achieving robust root systems. The first is the use of phosphite-based technology in the foliar feeds PK VEG and PK MAXX+. The biostimulating action of phosphite, enhancing nutrient movement in the plant, is particularly crucial in promoting root development especially when drought or excessively wet conditions may restrict normal root growth. (See article: New research confirms phosphites stimulate root growth)

PK VEG is a concentrated potassium phosphite liquid (0-42-28), while PK MAXX+ combines phosphite Phosphorus with phosphate for improved root formation. PK MAXX+ has the added benefit of supplying a range of secondary nutrients and essential trace elements ensuring access to key nutrients and so helping maintain more uniform growth patterns even under stressful growing conditions.

The second option is the use of natural biostimulant Stimplex: a liquid seaweed extract based on North Atlantic seaweed Ascophyllum Nodosum. Seaweed supplements are known to many growers for their ability to promote root growth but recent research has shown that Stimplex, rather than containing supplementary plant auxins and cytokinins as originally thought, actually induces the plant’s own production of these natural growth substances, thereby stimulating cell division and regulating cell elongation in a natural growth pattern. This effect together with the amino acids and organic sugars in Stimplex also provides effective help for brassicas in achieving large, efficient root systems.


A vigorous, well-nourished plant with robust and healthy roots already forms the basis for a more resilient crop. Achieving a rapid vigorous establishment with the help of an early application of PK VEG or PK MAXX+ will help boost your crop’s natural ability to tolerate disease, pest and environmental stresses through all stages of growth.

Importantly, PK VEG, in addition to its 42% phosphite component, contains high levels of plant available potassium which also plays a vital role in health and disease resistance maintaining pressure balances across cell walls and regulating the production and movement of starch and sugars.

For further reduction in the impact of drought, salinity and temperature stress on growth, Stimplex, has its own unique way of increasing resilience. It contains a matrix of amino acids that stimulate protein synthesis to strengthen cell membranes and as the plant is put under stress, it triggers the plant’s natural processes to help mitigate against any negative effects. Plants under temperature and drought stress build-up plant toxins and the stimulants in Stimplex, for example, has been shown to increase the production of enzymes (antioxidants) that break down these toxins.


Now let’s turn to aiding recovery. Of course, we know that prevention is better than a cure. Improving health, vigour and resilience at an early stage can reduce the impact of environmental factors and disease pressure but biostimulants can also aid plant recovery.

Extra root growth and increased nutrient mobility help recovering plants gain access to key nutrients. Under difficult conditions, PK MAXX+, PK VEG and Stimplex can stimulate not only rooting but also vegetative growth, helping to replace damaged leaf tissue; returning the crop more rapidly to the production programme.


Including phosphite-based nutrients PK MAXX+ or PK VEG as a supplement to your standard fertiliser programme will promote healthy rootthe evelopment, more efficient nutrient uptake and in turn increase resilience. However, for maximum resistance to and recovery from stress, we recommend combining your foliar phosphite with the natural biostimulant Stimplex. Particularly when used as a proactive programme on brassicas, Stimplex will provide that extra level of natural resilience.

All products are formulated as easy to use solutions for maximum tank-mix compatibility and ready incorporation into your current spray regime.

To discuss these nutrition strategies or any other related issues you can call James Thornalley on Tel. 07715 217421

Video Links (Acadian Seaplants Ltd on YouTube)
Stimplex(r) is a registered trademark of Acadian Seaplants Ltd.

Stimulating root development (watermelon)

Tomatoes resist drought stress

Lettuce and salinity stress


Related news items: 
Effective Calcium application
Phosphites stimulate root development
Stimplex case study – nutrient use efficiency