Are Basic Substances a Key to Sustainable Pest and Disease Management in Agriculture? An Open Field Perspective.

Pathogens and pests constantly challenge food security and safety worldwide. The use of plant protection products to manage them raises concerns related to human health, the environment, and economic costs. Basic substances are active, non-toxic compounds that are not predominantly used as plant protection products but hold potential in crop protection. Basic substances' attention is rising due to their safety and cost-effectiveness. However, data on their protection levels in crop protection strategies are lacking. In this review, we critically analyzed the literature concerning the field application of known and potential basic substances for managing diseases and pests, investigating their efficacy and potential integration into plant protection programs. Case studies related to grapevine, potato, and fruit protection from pre- and post-harvest diseases and pests were considered. In specific cases, basic substances and chitosan in particular, could complement or even substitute plant protection products, either chemicals or biologicals, but their efficacy varied greatly according to various factors, including the origin of the substance, the crop, the pathogen or pest, and the timing and method of application. Therefore, a careful evaluation of the field application is needed to promote the successful use of basic substances in sustainable pest management strategies in specific contexts.

Use of Chitosan and Other Natural Compounds Alone or in Different Strategies with Copper Hydroxide for Control of Grapevine Downy Mildew.

Grapevine downy mildew (GDM) is one of the most serious diseases of grapevines. Limitations to the use of copper-based products in organic agriculture according to the European Union (EU) regulation EU/2002/473 and the later EU Commission implementing regulation 2018/1981 have promoted a search for alternatives. This 5-year field trial evaluated the effectiveness of several strategies against GDM using different chitosan-based formulations and application rates in comparison with other natural compounds applied individually or with copper hydroxide. Trials were performed in commercial vineyards with different environmental conditions and grapevine cultivars. For the natural compounds applied as individual treatments, a 0.5%/0.8% chitosan formulation provided the best protection against GDM; the other compounds and formulations were less effective. When copper hydroxide use was halved by combining it with the natural compounds according to three different strategies, the GDM incidence, severity, and McKinney index were reduced, particularly for copper hydroxide applied in combination with the 0.5%/0.8% chitosan formulation. The 0.5%/0.8% chitosan formulation alone and with copper hydroxide provided good protection against GDM during both high-pressure and low-pressure disease seasons. Therefore, chitosan represents a good alternative to copper formulations for the control of GDM and both organic and integrated disease management.