The fungal genus Fusarium causes several diseases that can reduce yields and quality and in some cases, even kill the crop. While there are many different pathogenic Fusarium species, some of the most damaging diseases are caused by strains of one species complex, Fusarium oxysporum.
Crop nutrition can impact two resistance mechanisms to reduce the incidence of Fusarium and other common plant pathogenic diseases in vegetable crops:
Calcium is an essential component in maintaining the cell wall structure of a plant. Poor calcium nutrition can increase the crop susceptibility to fungi that can enter the xylem and dissolve cell walls causing the plant to wilt.
Calcium is also important to the stability and function of plant membranes. When calcium is deficient, the membrane can leak sugars and amino acids, which can stimulate the infection by pathogens.
Studies show that susceptibility to fusarium is much greater in the presence of ammonium nitrogen compared to nitrate nitrogen. A study also found that nitrate-nitrogen inhibits disease development and decreases the effects of fusaric acid – a toxin released by pathogens. This makes it critical to pay attention to your sources of nitrogen.
Laboratory studies show that nitrate-N suppresses the growth of F. oxysporum spores while ammonium-N enhances spore growth.
Fusarium spp. are favored by acidic soil conditions and soils with higher pH tend to show a decrease in disease severity. Even though the average soil pH along most of the California coast is greater than 7, all ammonium-based nitrogen fertilizers, including ammonium nitrate, create sites of acidity, which increase the risk of Fusarium infection. YaraLiva® Calcium Nitrate does not induce a residual acid reaction in the rhizosphere and thus can help suppress fusarium development.
Last, don’t forget about potassium! Plants that are deficient in potassium have impaired protein synthesis and can accumulate simple N compounds (amides), which are used by invading plant pathogens. Potassium can also prevent disease attacks by promoting the development of thicker outer walls in epidermal cells.
Learn more about calcium nitrate for fruits and vegetable crops.