New 2,4-D Formulation Can Reduce Citrus Splitting

Researchers have demonstrated how an early application of the plant hormone 2,4-D can significantly reduce fruit cracking (also known as fruit splitting) in citrus crops — a major economic challenge worldwide. The researchers are from the Mediterranean Agroforestry Institute at the Polytechnic University of Valencia and Valencian Institute of Agrarian Research in Spain. Their work complements pioneering studies conducted in the 1990s by Manuel Agustí. 

Citrus cracking occurs when the fruit’s pulp grows faster than its skin — typically following the first autumn rains. If the rind fails to expand at the same pace, it eventually ruptures. This leads to losses that can reach up to 40% of the harvest in mandarins — such as the Nova variety — and certain types of oranges, such as navels.

According to Carlos Mesejo, one of the researchers, orange and mandarin varieties with very thin skin that adheres tightly to the pulp are highly vulnerable to fruit cracking.

“When the pulp grows faster than the skin, the rind cannot withstand the internal pressure, and a fissure appears, ultimately resulting in the fruit cracking open,” Mesejo explained.

The study demonstrates that applying 2,4-dichlorophenoxyacetic acid (2,4-D) — specifically its new dimethylamine salt formulation — when the cell expansion stage begins can reduce fruit cracking by up to 70%. The treatment does not negatively affect fruit size or quality.

“The secret lies in strengthening the fruit’s skin from the inside out,” Mesejo said. “Thanks to this treatment, the cells in the rind become larger, more flexible and possess thicker walls. This gives the skin a greater capacity to stretch as the fruit grows without rupturing — which explains both the rationale behind applying 2,4-D and the critical importance of the precise timing of the treatment.”

One of the key advantages of this new 2,4-D formulation for reducing cracking is that it does not require the application of large quantities. Success depends on applying it at the exact right moment.

“We have achieved excellent results with just a single application during this early stage,” Mesejo said. “It is important to ensure that the majority of the fruits on the tree are thoroughly wetted, as the treatment’s effect acts directly upon the outer layer of the rind. In some instances, a single targeted treatment resulted in a reduction of damaged fruits by nearly half.”

The study, published in the Journal of Agriculture and Food Research, was conducted in mandarin plantations owned by independent growers as well as those belonging to the Agrihold group.

Source: Polytechnic University of Valencia