Farmers have been struggling for centuries trying to grow the best vegetables, fruits, grains and legumes for us, the consumers. And we should not take for granted their valuable work. In their day to day life, they have to face numerous challenges, which includes post-harvest pests and diseases.  

Some of the problems that post-harvest crops can face include shortened shelf life, limited market availability and a reduction of the quality, just to mention some. Let’s take a look at the most prevalent pests and diseases, and how to tackle them in a sustainable way. 

Common Post-Harvest Pests and Diseases 

1. Fungal diseases: All of us have seen at any point in our lives some green mold or gray mold in fruits. And this is caused by none other than fungi such as Penicillium digitatum or Botrytis cinerea. They are known to appear in storage environments, and for quickly deteriorating the produce.
2. Bacterial pathogens: Bacteria like Erwinia carotovora can lead to soft rot in vegetables such as carrots, potatoes, and tomatoes. Typically, the infection begins in minor injuries on the produce, providing optimal circumstances for bacterial proliferation. This leads to the development of soft, mushy produce that can rapidly become unmarketable.
3. Insect pests: In stored grains and legumes, insect pests such as the grain weevil and rice moth can cause a reduction in quality and contamination. Their presence often goes unnoticed until considerable damage has already taken place.
4. Post-harvest mites: Storage mites, like Acarus siro, flourish in damp, warm storage areas and can result in substantial harm to stored grains, flour, and dried foods. Infestations of mites not only diminish food quality but can also incite allergic responses in humans. 

How to Manage Post-Harvest Pests and Diseases
 

Microbial biocontrol offers an environmentally friendly alternative to synthetic chemicals. These methods harness the natural abilities of helpful microorganisms, like bacteria, fungi, and yeasts, to fight harmful pests and diseases without posing risks to the environment or human health. 

• Biocontrol fungi such as Trichoderma spp. are successful in suppressing the development of post-harvest pathogens. These fungi compete with harmful species by occupying the identical ecological niche or generating enzymes that degrade pathogen cell walls. 

• Bacillus subtilis is an effective bacterial agent capable of inhibiting several post-harvest diseases. Through the production of antimicrobial substances, Bacillus spp. hinder the proliferation of bacteria and fungi that cause spoilage on crops. 

• Bacterial strains such as Beauveria bassiana have been shown to successfully control insect pests in stored agricultural products. These bacteria infiltrate the pest’s body, ultimately causing their demise without harming the stored crops. 

• Post-harvest probiotic solutions emerging studies are looking into the potential benefits of probiotics for post-harvest crops. Certain types of bacteria such as Lactobacillus have been found to decrease spoilage in fruits and vegetables by competing with harmful pathogens. 

Case Study: Post-harvest Biocontrol in Citrus Farming
 

DARWIN Bioprospecting Excellence has been at the forefront of developing microbial biocontrol strategies for industries such as agriculture. For example, through the POSTHARVESTLIFE project, DARWIN is tackling the post-harvest fungi Penicillium digitatum and Galactomyces citri-aurantii, which cause severe losses in citrus fruits. By isolating specific microbial strains, which are naturally present in the fruits, we can suppress these pathogens. DARWIN is helping farmers reduce losses and minimize the use of harmful chemicals.