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Urban Horticulturists See the Benefits of Mycorrhizal Fungi

Friday, May 8, 2020 | Troy Buechel

Lately, we have seen a lot of enthusiasm for urban horticulture and those who practice it are discovering the benefits of a healthy soil. However, due to the heat islands and wind factor on the roof of buildings, growing conditions can be stressful for plants.

There are numerous challenges, but they can be minimized by using mycorrhizal fungi inoculants and/or other beneficial soil organisms (bacteria, beneficial nematodes, earthworms, etc.) to increase the plant’s resistance to these difficult environmental conditions.

A majority of plant species will benefit from mycorrhizal fungi

The vast majority of plant species used in urban horticulture will benefit from the presence of mycorrhizal fungi.  Inoculants such as MYKE PRO Nursery or PRO-MIX PUR MYCORRHIZAE ZEOLITE can be introduced at planting or can be pre-mixed into soilless growing media, such as the PRO-MIX MYCORRHIZAE line of products.  They are readily available to colonize plant roots that come in contact with the mycorrhizal fungi to help them get established in their new soil environment.

Here are a few examples of plants that have responded well to mycorrhizal inoculants (Figures 1, 2 and 3):

• Urban vegetable crops in soil or trays: onion, garlic, carrots, potatoes, tomatoes, peppers, cucurbits, asparagus, herbs and lettuce
• Annuals in planters or flower beds: salvia, ornamental grasses, canna, ferns, aloe, gerbera
• Perennials in containers or flower beds: hosta, rose bush, lavender, thyme, purple coneflower, beebalm and nepeta
• Trees and shrubs in the landscape: fruit trees, gleditsia, juniper, thujas, maples, lilacs and elms

Figure 1.  The chives on the right were inoculated with mycorrhizal fungi and has greater root and shoot growth vs. the chives on the left that were not inoculated.  Source: Premier Tech

Figure 2. The gerbera on the right was inoculated with mycorrhizal fungi and has more roots and more advanced flowering than the non-inoculated gerbera on the left. Source: Premier Tech

Figure 3. The citrus plant on the right was inoculated with mycorrhizal fungi.  Notice it has more roots than the plant on the left without mycorrhizal fungi. Source: Premier Tech 

The main benefits of mycorrhizae include:

• Better nutrient uptake (including phosphorus, copper, zinc and manganese)
• Greater resistance to stresses related to transplanting, nutrient deficiencies, root rot and drought
• Optimal recovery and growth after transplanting
• Increase in plant vigor, flowering and fruit/vegetable production

The use of mycorrhizal inoculants is an interesting solution to help plants withstand difficult environmental conditions. They are particularly useful to help plants survive and grow, despite the excessive heat and lack of water they may experience more often due to climate change, especially in urban environments.

A few practical applications

The effects of mycorrhizae are important especially during stress episodes experienced by the plant. The greater the stress, the more the plant will rely on the mycorrhizae's cultural help and the more the plant benefits.  However, depending on the plant species, the measurable benefits of mycorrhizae are variable (Table 1).

Table 1. Effect of mycorrhizae on various plant species compared with non-mycorrhized plants in the table below:

For more information, contact your Premier Tech Grower Services Representative:

Ed Bloodnick Horticulture Director US-South East	JoAnn Peery Horticulture Specialist US-Central, Canada-Central	Lance Lawnson Horticulture Specialist US-West, Canada-West
Troy Buechel Horticulture Specialist US-North East	Susan Parent Horticulture Specialist Canada-East, US-New England	Jose Chen Lopez Horticulture Specialist Mexico, Latin & South America