Salicylic acid for plants. 38

Salicylic Acid for Plants.

The use of Salicylic Acid on plants has several benefits to plants. Salicylic Acid (SA) is a key component of aspirin, and bark extracts from Witch Hazel have been in use to treat pain and inflammation for thousands of years. In 1933, SA was first proposed to develop acquired immunity after disease infection.

Most of our knowledge about plant immune signalling has been recent after the discovery that salicylic acids (SA) role in plants is as a defence signal from within the plant.

This blog dovetails nicely with our recent article on DIY pest control, and our recent research into two novel bioactive compounds on root growth.

SA affects several plant processes.

1. Abiotic stresses: SA impacts on several abiotic stresses including cold tolerance, temperature extremes, drought tolerance, tolerance to UV radiation, and soil salinity tolerance.
2. Induces resistance to disease stress.

Foliar applications of SA affect several aspects of plant growth and development¹Hayat Q, Hayat S, Irfan M, Ahmad A. Effect of exogenous salicylic acid under changing environment: A review. Environ Exp Bot. 2009;68:14–25. doi: 10.1016/j.envexpbot.2009.08.005. ²Khan MIR, Fatma M, Per TS, Anjum NA, Khan NA (2015) Salicylic acid-induced abiotic stress tolerance and underlying mechanisms in plants. Front Plant Sci 6:462. ³Malamy, J., Hennig, J., and Klessig, D. F. (1992). Temperature-dependent induction of salicylic acid and its conjugates during the resistance response to tobacco mosaic virus infection. Plant Cell 4, 359. doi: 10.1105/tpc.4.3.359.

For instance exogenous applications of SA on plants affects:

1. The germinaton of seeds;
2. The growth of plants;
3. Root development;
4. Photosynthesis;
5. Plant respiration and
6. the Krebs cycle.

Salicylic Acid vs Other Plant Hormones/Bio-stimulants:

We have written a detailed overview of Bio-stimulants in these two articles. Article 1 and Article 2. However, SA has some unique properties in comparison to other plant hormones or bio-stimulants.

Salicylic Acid.

SA has roles in abiotic stresses such as salinity, drought, cold, heavy metal and heat stress. Plant physiological processes that SA regulates are photosynthesis, stomatal opening and closing, enzymes, nutrient uptake, and overall plant growth and development (seed germination, vegetative growth, flowering, and senescence).

Humic Acid.

Humic acid improves and stimulates plant growth, suppresses diseases and promotes more stress resistance.

Fulvic Acid.

Fulvic acid increases the root system and promotes seed germination, and growth rate.

Cytokinin.

Cytokinin is a hormone that regulates the rate of cell division, gas exchange, and root development.

Gibberellic Acid.

Gibberellic acid is important in cell growth and elongation. It also promotes seed germination and seedling development. If you suppress gibberellic acid levels it causes turf to become stunted.

Absisic Acid.

Abscisic acid is a growth inhibitor that extends dormancy, limits water use and stops cell division, elongation and growth.

Systemic Acquired Resistance (SAR).

Systemic Acquired Resistance (SAR) is a long lasting and broad spectrum defence mechanism that occurs when a pathogen infects a turf grass plant.

After infection, a pathogen triggers what we call the SA pathway. This then induces defence response genes in the plant, and results in PR protein production.

The other role of SA in turf grass management, is as a plant hormone that helps regulate various physiological processes.

Here are a few key roles of SA in turf grass:

Disease resistance using Salicylic Acid for Plants:

In short, SA boosts a plant’s immune system. SA enhances the plant’s resistance to several diseases, in particular fungi or bacteria.

It activates defence mechanisms inside the plant, and makes it less susceptible to infections. For example, foliar applications of SA cause systemic acquired resistance (SAR) in plants, and provide protection against various biotic stresses.⁴Yang Y, Shah J, Klessig DF. 1997. Signal perception and transduction in plant defence responses. Genes ant1 Develop 11:1621-39.

Fungal diseases:

SA enhances turf grass resistance against diseases such as dollar spot and brown patch. It activates defence responses in the plant, which include the production of antimicrobial compounds and the reinforcement of cell walls. This makes it more difficult for fungi to infect the turf grass.

In fact, It has been shown to be very effective against grey leaf spot on turf type perennial ryegrass, and gives a significant decrease in disease⁵Rahman A, Kuldau GA, Uddin W. Induction of salicylic acid-mediated defence response in perennial ryegrass against infection by Magnaporthe oryzae. Phytopathology. 2014 Jun;104(6):614-23..

Bacterial diseases:

SA also helps turf grass combat bacterial diseases like bacterial wilt and bacterial leaf blight. If you pre-treat plants with SA, it reduces disease symptoms of bacterial wilt in both ‘Penn-A4’ and ‘Tyee’ creeping bentgrass.

SA reduces bacterial disease in these cultivars under both ideal and high temperature treatments. At 23 °C and 35 °C respectively, disease severity in plants treated with SA was less than in the untreated control plants.⁶Sha Liu, Joseph Vargas, Emily Merewitz, Jasmonic and salicylic acid effects on bacterial etiolation and decline disease of creeping bentgrass, Crop Protection Volume 109, July 2018, Pages 9-16

SA stimulates the plant’s immune system to produce defence-related proteins, enzymes, and chemicals. All of these inhibit bacterial growth and limit disease progression.

Viral diseases:

While SA doesn’t directly target viruses, it indirectly enhances turf grass resistance to them. By activating systemic acquired resistance (SAR), SA helps the plant produce antiviral proteins that hinder the spread and replication of viruses.

Nematode Resistance using Salicylic Acid:

SA increases turf grass resistance against nematodes. Nematodes are microscopic worms that damage turf grass roots, and result in stunted growth and decline.

SA induces defence mechanisms in the plant. These include the release of nematode-repellent chemicals, which deter nematode feeding⁷Molinari S, Salicylic acid as an elicitor of resistance to root-knot nematodes in Tomato, ISHS Acta Horticulturae 789: XV Meeting of the EUCARPIA Tomato Working Group ⁸El-Sherif, A.G.;* Gad, S. B.; **Khalil, A.M. & ***Mohamedy, Rabab H.E. 2015. Impact of Four Organic Acids on Meloidogyne Incognita Infecting Tomato Plants under Greenhouse Conditions, Global Journal of Biology, Agriculture and Health Sciences, Vol.4(2):94-100.

Tomato plants treated with SA showed a 20 to 25% reduction in root knot egg numbers compared to an untreated control⁹Molinari, Sergio. (2008). Salicylic Acid as an Elicitor of Resistance to Root-Knot Nematodes in Tomato. Acta horticulturae. 789. 119-125. 10.17660/ActaHortic.2008.789.15. . Similar results were seen in 2017 by Martínez-Medina et al¹⁰Martínez-Medina A., Fernandez I., Lok G. B., Pozo M. J., Pieterse C. M. J., Van Wees S. C. M. (2017). Shifting from priming of salicylic acid- to jasmonic acid-regulated defences by Trichoderma protects tomato against the root knot nematode Meloidogyne incognita. New Phytol. 213, 1363–1377. 10.1111/nph.14251.

Insect effects:

Research has shown it repels certain insects such as thrips¹¹O. Ozinger, Effects of methy salicylate, methyl jasmonate and Cis-Jasmone on thrips Tabaci Lindeman, 2012,University of Natural Resources and Life Sciences, Vienna Division of Plant Protection , caterpillars¹²Iversonlo A, Inverson L, and Eshita S, The Effects of Surface-Applied Jasmonic and Salicylic Acids on Caterpillar Growth and Damage to Tomato Plants, OHIO J SCI 101 (5):S)O-94, 2001, and indirect effects on mite mortality¹³Homayoonzadeh M, Moeini P, Khalil Talebi K, Allahyari H,Torabi E, Michaud JP, Physiological responses of plants and mites to salicylic acid improve the efficacy of spirodiclofen for controlling Tetranychus urticae (Acari: Tetranychidae) on greenhouse tomatoes, Exp Appl Acarol. 2020 Nov;82(3):319-333 .¹⁴Vilela de Resende JT, Rafael Matos R, Zeffa DM, Constantino LV, Alves SM, Ventura MU, Resende NCV, Youssef K, Relationship between salicylic acid and resistance to mite in strawberry, Folia Hort. 33(1) (2021): 107–119.

Stress Tolerance using Salicylic Acid:

Turf grass often faces environmental stressors, such as drought, heat, or cold. SA helps plants cope with these stresses as it regulates various stress-responsive genes and biochemical pathways. It improves the resilience of turf grass,and allows it to withstand adverse conditions more effectively.

Growth regulation:

SA influences the growth and development of turfgrass. It promotes root growth, leading to a healthier and more robust root system. Additionally, it can regulate shoot growth, helping to maintain a balanced growth pattern and overall turf quality.

Photosynthesis and chlorophyll production:

Finally, SA also enhances photosynthesis, which is crucial for the production of energy and the maintenance of turf grass health. It increases chlorophyll content, which leads to greener and more vibrant turf.

The role of SA content by certain abiotic and biotic factors¹⁵Rossi CAM 1, Marchetta EJR, Kim JH, Castroverde CDM, Molecular regulation of the salicylic acid hormone pathway in plants under changing environmental conditions, Trends in Biochemical Sciences, Volume 48, Issue 8, August 2023, Pages 699-712 (credits: Rossi et al. 2023; DOI: 10.1016/j.tibs.2023.05.004).

Salicylic Acid Use on Cool Season Turf.

Cool-season turf is highly susceptible to temperature extremes and this has major impacts on growth. Research shows that SA increases heat tolerance on both kentucky bluegrass and tall fescue, and increases turfgrass quality.¹⁶Larkindale, J, and Huang, B. (2004). Thermotolerance and antioxidant systems in Agrostis stolonifera: involvement of salicylic acid, abscisic acid, calcium, hydrogen peroxide, and ethylene. J. Plant Physiol. 161, 405–413.

In a 2019 growth chamber study¹⁷Zhang X and Goatley M, Evaluating the effects of SA and pigment sources, 2019 https://issuu.com/leadingedgepubs/docs/va-turfgrass-2019-jan-feb/s/10135194, salicylic acid at 3.5g/L mM, 7g/L, and 1.4g/L plus pigment improved the colour of creeping bentgrass under heat and mild drought stress at 42 and 56 d after initial treatment.

• The results suggest that the role of SA in plants with pigment is to block UV-B radiation and protect the plants photosynthetic function from UV-B injury.
• The results indicate a synergy between SA and the pigment for turf quality improvement under heat and mild drought stress conditions.

How to Apply Salicylic Acid to Plants?

There have been two issues associated with SA and its use on plants.

• How to apply an amount that actually works? It is not water soluble so it isn’t just a case of dissolving this and then applying it to vegetation.
• How to apply high loads of SA without any damage to the plant.

The Delopment of a Salicylic Acid Bio-stimulant.

In 2019 we began to investigate how to apply high loads of SA, and in 2021 we developed a way of dissolving 200g in 1L of product. To achieve this same loading at home you will need to dissolve over 650 aspirin in a Litre of water.

Currently this high loading of SA is only available in Vertmax Duo. However in the future we are looking at this being available as a standalone product without any pigment.

Vertmax Duo: A Premium Turf Pigment with Salicylic Acid.

The development of Vertmax Duo began shortly after the launch of Bayer’s Stressgard products. The Stressgard range offers a colourant and biostimulant pre-mixed with certain fungicides.

Why Vertmax Duo?

Vertmax Duo turf pigment is the only product on the market that contains 200g/L of salicylic acid. One application gives an immediate colour response together with all the potential benefits listed below.

It’s formulation also contains adjuvants and stickers to help with coverage, longevity and uptake.

Benefits of Vertmax Duo.

• Because of its excellent tank compatibility you can mix this with all fungicides, fertilisers and insecticides. You have not got to use one brand to get the benefits of SA.
• Salicylic acid increases disease resistance plus heat and drought tolerance of turf.
• No stain formulation.
• Increases root growth and lateral branching.
• Is continuously being researched and improved.
• Higher quality playing surfaces.

Please feel free to check out more information on Vertmax Duo or contact us directly. To put it another way, why prevent your playing surface from being at its best?

Vertmax Duo label

Vertmax Duo presentation.

Buy Vertmax Duo.

Vertmax Duo comes in 1 L containers. Buy Here If you wish to purchase this unique colourant and biostimulant packed full of Salicylic Acid.