Testing the effectiveness of various fertilizers, hormones and conditioners needs to be done with a reasonably sized sample, but often with the best of intentions the difference between the control and the samples is difficult to observe. This would require laboratory analysis and may show only a few percentage points difference and not really worth the effort, so instead I have looked for a significant impact that can be easily applied. This is not a rigorous scientific enquiry but a way of looking for an easily applied protocol to a variety of Proteaceae that have a wide range of soil, water, nutrient, and climate demands.
What follows is a description of various products currently available and what their effects can be when used in manipulating motherstock plants.
Auxins are used in the rooting of cuttings and are available in various strengths, liquid and powder form. They promote cell division and root formation. I generally use a powder IBA (number 2) for other softwood cuttings and a liquid IBA (4000ppm – 5 second dip) for the harder Proteaceae and this can be diluted somewhat according to the age of the stems.
Coco fibre can be a problem in that it needs to be soaked and rinsed to reduce the salt content, especially for sensitive Proteaceae seedlings, otherwise it holds water well and the texture is good.
Peatmoss is a better alternative to coco fibre as the salt content is less and can be mixed 50/50 with well matured pine bark. Some Peatmoss formulations have a higher salt content, requiring flushing with water to get the correct Ph, around 5.5
Compost can contain all sorts of unwanted elements unless it has been treated correctly.
All Proteaceae are sensitive to phosphates, some more than others so it would be better to be conservative with its proportion to the other elements.
An 8-1-5 slow-release granular fertilizer added to the potting soil and while this is the proportion readily available for roses, a slow release would be better. Fertigation works well, but a build-up of salts can occur and a special mixing tank and pump would be needed while the 8-1-5 slow-release is granular and is easier to apply. Remember that in nature Proteaceae thrive in a nutrient poor environment.
Fulvic acid enhances cell division and elongation. Root growth is magnified with obvious benefits. As a foliar spray, fulvic acid increases the plant’s oxygen uptake capacity with an associated increase in chlorophyll production and an increase in the permeability of plant membranes, improving the uptake of nutrients. I use fulvic acid mixed with seaweed extract all the time, the ratio used is 5 parts seaweed extract to 7 parts fulvic acid.
Micronutrients: I add these more in the hope they may help if the plant is deficient in some of these elements as a potting medium like peat moss or river sand may be lacking in some.
Salicylic acid. Asprin is easily obtainable, however adding a few headache pills does not work well enough in this instance as the concentration cannot be accurately determined. Rather be conservative and use salycilic acid at a concentration of 200mg per liter of water. Too high a concentration can be detrimental.. Salicylic acid is available through laboratory suppliers and there has been considerable research so there is much deeper information on the Internet. Salicylic acid is dissolved in Isopropyl alcohol and care is needed when mixing with water to avoid a precipitate forming.
Seaweed extract is a very useful product that can be incorporated into most spray programs. It has a higher concentration of auxins to cytokinins and enhances root growth as well as leaves. When mixed 5:7 ( 10ml : 14ml/ litre) with fulvic acid is a great foliar spray for cuttings and grafts and can be applied at weekly intervals. A pot plant suffering from water stress (blocked dripper, etc.) can be rescued by standing it in a tray of seaweed extract and salicylic acid for a few hours.
Smoke condensate: There are two ways of making smoke water, either by bubbling smoke through water or collecting the smoke condensate of heated wood. The condensate is “stronger” but the concentration cannot be determined and a too strong mix with water “burnt” the leaves of seedlings when sprayed. Rather have too little to start with! The value of priming seeds with smoke water to enhance germination is well documented and is recommended, however smoke water has little or no effect on the germination of Leucospermum seeds. I did some experiments to determine the effect of smoke water on phytopthora but there was little to show. Healthy rootstock and seedlings were sprayed with smoke water twice a week apart and then inoculated with phytopthora at week 3. The phytopthora was cultured from one of my infected plants onto agar in petri dishes, positively identified and then the agar was placed in direct contact with the roots. There were two concentrations of smoke water with appropriate controls for a total of 50 plants inoculated. All the plants died. It is possible that the smoke water application was too little too late or too early and requires a greater interrogation. Smoke water has a low ph. and can be a useful additive to lower the ph. in the potting soil. It also has a wide range of other additives that may be beneficial to Proteaceae that have evolved in a wide range of soil types.
Tricoderma harzianum: There has been plenty of research done on mycorrhiza and findings are available on the Internet. As a biological control it is reputed to counter pathogens in the soil when the incidence is not high, however another function is to assist in the uptake of nutrients which includes phosphates that most (not all) Proteaceae find toxic to varying degrees. If Proteaceae are being fertilised with only a small amount of Phosphate, the uptake will be enhanced by the Mycorrhiza and could result in negative effects from an over uptake of Phosphorus. .
The form I used was in a powder that is soluble in water so is easy enough to apply via a watering can. It is an inoculant so it will grow and develop in time to colonise a greater area.
The dosage recommended by one supplier is 25 grams in 55 litres of water and this will be enough to inoculate 550 one litre pots of peatmoss– 50 ml initially and then a follow up of another 50ml two weeks later. This will hopefully stop the water dripping out of the bottom.
Tricoderma will only multiply in the presence of roots, otherwise it is dormant till then, so adding to potting soil for seedlings will not be effective until after the necessary roots have formed.
Mycorrhiza will be eliminated with systemics and soil drenches with disinfectants
Clean water: Local authority water is normally clean but, in some areas, can carry pathogens. Well/wellpoint/borehole water should be considered contaminated, tested and treated if necessary. If a dripper system is utilized it also has to be filtered so the water should be passed through an online filter to remove the larger particles and then through the smallest possible (5 micron) that can filter out some pathogens. If the water is slowly passed over an ultraviolet light (as used in ornamental fish ponds), most pathogens would have been eliminated. Sodium hypochlorite (bleach) can be used, but not with tricoderma at the receiving end. A sanitizer like Sporekill is effective, but again will kill tricoderma.
I have in my movements in the Fynbos come across three naturally occurring Proteaceae hybrids, one I multiplied but then lost to phytopthora and the other did not respond to seed, cuttings or grafts. I still lament the lost opportunity and realising I could have done better, put more accuracy into my efforts. Very recently I was introduced to another single Protea hybrid that must be at least twenty plus years old and it seems as if there are a few cuttings and grafts that are showing promise with seeds awaiting the onset of cooler weather to initiate germination.
It is my hope that my findings may be used by others in the future.
Thanks