February 2023 - 30

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Managing Greenhouse Root Diseases
in Hanging Baskets
Nathan Wallace-Springer
Horticulture Specialist
Premier Tech
The battle to protect plants against root disease is a constant struggle for both
professional and home growers alike. This reality holds particularly true for
growers of hanging baskets, which often have unique challenges to consider
in their growing operations. For example, hanging baskets typically stay
wetter for longer periods of time as they contain a greater volume of growing
medium by volume and since they are commonly grown in combination with
other plant species that require their own unique fertilizer and water needs.
(Ex. Petunia, calibrachoa, bacopa, begonia, geranium, and pansy planted together
in the spring)
Nonetheless, for root diseases to develop, three components must
exist: 1) a susceptible host plant, 2) an environment that is conducive to
a particular pathogen, and 3) that a pathogen is present. However, while
there are many pathogens that cause root disease in horticultural crops, the
five of the most common pathogens pertaining to hanging basket root
diseases are: Fusarium, Phytophthora, Pythium, Rhizoctonia, and Thielaviopsis.
Generally speaking, root diseases occur in stages. In the initial stages, a
healthy hanging basket must first be made susceptible to root disease through
some external factor, such as overfertilizing or overwatering. Then, if the
cause of the cultural stress is not identified or corrected, the plants inside the
hanging basket can weaken to the point that it can become infected by the
plant pathogen, if present. Hanging baskets that experience root disease will
exhibit characteristics of nutrition disorders such as stunted growth, discolored
leaves and/or interveinal chlorosis, since roots are damaged and unable to take
up nutrients. As disease progresses, plants can display wilted leaves, leaf loss,
soft " mushy " stems, brown or black roots, or plant death itself.
So, how is a hanging basket grower to combat these root diseases organisms
from occurring in their greenhouses?
Circle 113
Understanding the potential threats and environmental conditions that can
affect plant health are the first steps a grower should take to prevent diseases
from developing in their greenhouse. Proper greenhouse sanitation practices
should be established, followed, and routinely adhered to as they serve as first
line of defense to combating these root diseases organisms.
Additionally, growers should begin by selecting the proper growing medium
for the season in which they are growing hanging basket crops. Next, identify
and correct environmental conditions that favor root diseases in the greenhouse,
such as poor airflow, high humidity, or overly wet conditions. Changing
crop management schedules can also help in this regard. For example, crops
should be watered in the morning rather than in the evenings so that plants do
not sit in saturated media throughout the night which can put them at risk.
Finally, hanging basket growers should consider using a growing media
that contains biological additives, such as PRO-MIX®
+ MYCORRHIZAETM
BIOFUNGICIDETM
, which helps to suppress the root zone pathogens Fusarium,
Pythium, and Rhizoctonia before the onset of disease. Eliminating these conditions
will greatly reduce the chances of root disease organisms to
persist in the greenhouse. Ultimately, the goal of root disease management
should be to reduce the level of disease below the economic damage threshold
or level of disease needed to cause a yield or quality loss. This can be accomplished
by taking a proactive approach, rather than a reactive approach, that
will save time, money, and energy in the long run.
LEARN MORE ABOUT COMMON
GREENHOUSE ROOT DISEASES CAUSES,
SYMPTOMS AND PREVENTION
https://bit.ly/3QtpowU
February 2023

Table of Contents for the Digital Edition of February 2023
