Innovative Foliar Treatments for Crop Nutrition and Protection

Dear Colleagues,

Foliar application of agricultural inputs—fertilizers, biostimulants, and plant protection products—is a strategy that complements interventions to the soil or growing substrate. However, several drawbacks hinder this approach from reaching its full potential: poor penetration through the leaf cuticle, low uptake via stomatal openings, limited translocation of systemic products from leaf tissues to the whole plant, damage to aerial plant organs due to overdosing, and reduced efficiency caused by inappropriate application timing or spray drift.

Innovative solutions have been developed over the past decade to address these challenges. Various nanoformulations and/or controlled-release formulations have been shown to enhance leaf uptake and translocation within the plant. One illustrative example involves nanoparticles of nutrient metal oligo-elements (e.g., Ca, Mg), trace elements (e.g., Fe, Cu, Zn, Mn, Mo), or beneficial semi-metal elements (e.g., Si or Se, used as inorganic biostimulants), which have demonstrated improved absorption and movement within plants following foliar application. Biopolymers have also been employed in the controlled-release formulation of plant protection products, including biological control agents. Unmanned aerial vehicles (UAVs or drones) allow for the precise application of inputs from optimal distances. When integrated with decision support systems, UAVs can improve application efficiency and reduce environmental impact. New classes of foliar-applied products have emerged. These include formulations that form reflective inorganic particle films on plant leaves to enhance tolerance to biotic and abiotic stress in horticultural crops. Antitranspirants, based on film-forming compounds or agents that modulate stomatal conductance, help improve drought tolerance. Foliar-applied biostimulants that promote nectar production can act as pollinator attractants. Similarly, foliar application of soil rhizobia has been shown to elicit plant defense mechanisms against diseases, chilling, or drought stress. Combining different foliar-applied agricultural inputs may further increase their efficacy. For instance, particle films can serve as carriers for foliar fertilizers or plant protection products.

This Special Issue welcomes contributions related to innovative foliar treatments aimed at achieving more sustainable and efficient crop nutrition and protection. We invite experts to submit original research manuscripts, research proposals or ideas, communications, technical notes, commentaries, and reviews or mini-reviews related to this complementary agronomic strategy.

Dr. Florin Oancea

Guest Editor

Dr. Florin Oancea
Guest Editor

Manuscript Submission Information

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• nutrient metal nanoparticles
• inorganic nanobiostimulant—Si, Se, Ti
• controlled released biopesticides
• second-generation biostimulants
• inorganic particle film forming products
• film-forming antitranspirants
• metabolic antitranspirants acting on stomata
• nectar enhancers as pollinator attractant
• soil microorganisms applied to leaves
• treatment for harnessing biological nitrogen fixation in phyllosphere
• precise foliar application by UAVs
• LiDAR-guided variable rate foliar application