September 2022 - 25

PLANT HEALTH
symptoms progress, you may see
brown dead spots on the leaves.
* Detection: Monitor media and
conduct plant analysis.
* Cure: Correct pH to between
5.0 and 7.0 in nutrient solutions.
Apply fertilizers, if needed. In
greenhouses, airflow can be low;
introducing horizontal airflow
at a rate of 0.3 to 1 m/s at
plant level can break the plant
boundary layer and increase the
transpiration rate to avoid calcium
deficiency in lettuce. The key with
this is that airflow needs to be
uniform for uniform plant growth.
IRON DEFICIENCY
* Cause: The most common cause
of iron deficiency is high pH in the
media and/or irrigation water. It
can also be caused by nutrient
imbalance.
* Symptoms: Iron deficiency shows
up in plants as yellowing between
leaf veins. Look for this symptom
to show up first on new growth.
* Detection: Monitor media and
conduct plant analysis.
* Cure: Correct the pH of the
nutrient solution. Apply iron
fertilizer, if needed.
MAGNESIUM DEFICIENCY
* Cause: Magnesium can be caused
by high media pH and/or nutrient
imbalance.
* Symptoms: Look for yellowing
between leaf veins as a symptom
of magnesium deficiency.
Magnesium deficiency usually
shows up first on lower to middle
leaves which helps distinguish it
from iron deficiency.
* Detection: Monitor media and
conduct plant analysis.
* Cure: Correct the pH of the
nutrient solution. Apply iron
fertilizer, if needed.
BORON TOXICITY
* Cause: Boron toxicity is caused
by applying too much boron to
plants. Of the nutrients commonly
applied as fertilizer, boron has
the narrowest range between
deficiency and toxicity. It is easy
to over-apply boron. Check and
double-check fertilizer calculations
before applying. It can also be in
irrigation water. It is important
to check levels in a water source
Seeding Smarter SolutionS For Better PerFormance
The road to better performance starts at the
AmericanHort Plug & Cutting Conference
As the premier event for young plant producers and growers from across the country, this
conference is the place to learn the newest and best strategies, technologies, and techniques
in the world of plugs and cuttings.
before using it and to account
for boron in the water when
adding boron fertilizer.
* Symptoms: Symptoms of boron
toxicity are yellow and dead
spots on leaf margins. You may
also see reduced root growth.
* Detection: Monitor media
and conduct plant analysis.
* Cure: Determine the source
of the excess boron and
correct it.
Elsa Sánchez is associate professor of
horticultural systems management,
Robert Berghage is associate professor
of horticulture, Thomas Ford is
Extension educator and Francesco
Di Gioia is assistant professor of
vegetable crop science, all at Penn
State University. Nick Flax is former
Extension education at Penn State
and current technical services
specialist at Ball Seed Co.
September 19-21, 2022 | Denver, CO
Join us for...
Grower-Focused Education
Experiencial Greenhouse Tour
Connection-Building Trade Show
Hands-On Workshops
REGISTER NOW at AmericanHort.org/Plug

https://www.americanhort.org/event/plug-and-cutting-conference/

September 2022

Table of Contents for the Digital Edition of September 2022