# First report of black pustule disease in sponge gourd (Luffa cylindrica) in northern Egypt and its biological management

## TL;DR

Black pustule disease caused by two fungi was first reported on sponge gourd in northern Egypt, and biological treatments like Bacillus subtilis reduced disease severity.

## Contribution

This is the first report of black pustule disease in Luffa cylindrica in Egypt, caused by Alternaria alternata and Fusarium equiseti, with effective biological control methods identified.

## Key findings

- Alternaria alternata and Fusarium equiseti were identified as the causal agents of black pustule disease in Luffa cylindrica in Egypt.
- Bacillus subtilis was the most effective bioagent in reducing disease severity, followed by Trichoderma harzianum and algae treatments.
- Seed treatments with T. harzianum and B. subtilis showed the greatest reduction in disease severity compared to other application methods.

## Abstract

In October 2022, black pustules were observed on the lower surface of sponge gourd (Luffa cylindrica) leaves in Kafer El-Dawar, North Egypt. Symptoms included abundant black pustules containing fungal conidia on plant leaves, which eventually led to the infected leaves drying out and dying.

Two causal fungi were isolated from symptomatic leaves and their pathogenicity was confirmed to induce typical disease symptoms. On the base on morphological features and further molecular identification, the isolated pathogens were identified as Alternaria alternata (accession No. PP197255), and Fusarium equiseti (accession No. PP197302). A survey was conducted to detect this disease on luffa plant leaves in northern Egypt, where luffa plants are cultivated. An attempt at biological control of this disease was made for two successive growing seasons under field conditions. BF, algae, Trichoderma harzianum and Bacillus subtilis were applied as seed treatments, and soil drenches were applied, followed by foliar spraying. Throughout the two seasons, the applied bioagent B. subtilis significantly reduced disease severity followed by the T. harzianum and algae treatments.

Seed treatment with two bioagents, T. harzianum and B. subtilis, had the greatest effect on disease severity, followed by soil drenching + foliar spray, soil drench only, and in that respective order. This is the first report of black pustules on the leaves of Luffa plants caused by Alternaria alternata and Fusarium equiseti in Egypt.