Tip Burn On Crops Grown Under CEA Conditions
Tip Burn On Crops Grown Under CEA Conditions Dr. Don C. Wilkerson, Professor Emeritus Department of Horticultural Sciences Texas A&M University College Station, Texas
What is Tip Burn?
Definition of Tip Burn • Tip burn or necrosis refers to the death of plant cells. • The affected tissue usually turns brown to black in color. • Necrotic symptoms may occur on any part of the plant but in this case are limited to leaf tips. • Tip burn may also include leaf edges or margins.
Recognizing the Symptoms
Examples… Tip & Marginal Burn (Necrosis) Marginal Necrosis Tip Necrosis Tomato
Examples… Tip & Marginal Burn (Necrosis) Marginal Necrosis Pepper
Examples… Tip & Marginal Burn (Necrosis) Tip Necrosis Strawberry
Examples… Tip & Marginal Burn (Necrosis) Marginal Necrosis Basil
Examples… Tip & Marginal Burn (Necrosis) Marginal Necrosis Tip Necrosis Cannabis
Examples… Location is Important… Inner Leaf Necrosis Lettuce
Examples… Location is Important… Outer Leaf Necrosis Lettuce
Chlorosis (Yellowing) Interveinal Chlorosis
Primary Causes… Deficiencies & Toxicities Sodium Chloride
Transpiration
Factors That Influence Transpiration • • • Temperature Humidity Daily Light Integral (DLI) Air Movement Substrate Moisture Root Development
Root Development & Transpiration
Tip Burn Case Study
Calcium Deficiency Role of Calcium in the Plant • • Essential Nutrient Limited Mobility Cell Wall Structure Cell Division & Elongation
Calcium Deficiency Conditions Leading to Symptoms • Rapid Growing Conditions • Low Transpiration Rate • Supply & Demand Adequate Ca Supply and Root Development
Calcium Deficiency Recognizing Symptoms • • • Inner Leaf Necrosis Inner Leaves Developing Leaves Strap-Like Leaves Brown Spots Leaf Necrosis
Calcium Deficiency Management Strategies • • • Match Nutrient Flow & Growth Rate Temperature Humidity Light Levels Air Flow CO 2 Levels Substrate Moisture
Calcium Deficiency Growth Rate Management Guidelines These Vary Widely Based on Geographic Location & Type of Production System • • • Evaluate Root Development Monitor Ca in Nutrient Solution (90 ppm) Light Levels (>15 mol m-2) Manage Air Flow Monitor Carbon Dioxide
Tip & Marginal Necrosis - Salts Role of Salts in Tip & Marginal Burn • • • Sodium & Chloride Other Specific Ions Extremely Mobile Fertility Related Water Relations
Tip & Marginal Necrosis - Salts Conditions Leading to Symptoms • • Sodium & Chloride Fertility Levels High Salts in Root Zone Root Development Low Humidity High Air Flow Substrate Moisture
Tip & Marginal Necrosis - Salts Recognizing Symptoms • • • Outer Leaves Brown Lesions Burned Appearance Tips & Margins Chlorosis Tip & Marginal Necrosis
Tip & Marginal Necrosis - Salts Management Strategies • • • Monitor Fertility Control Air Flow Humidity Substrate Moisture Foliar Hydration
Tip & Marginal Necrosis - Salts Management Guidelines These Vary Widely Based on Geographic Location & Type of Production System • • • Evaluate Root Development Monitor EC of Nutrient Solution (1. 0 – 2. 0 m. S/cm) Leach Substrates as Necessary Light Levels Reduce Air Flow Under Low Humidity Avoid Extreme Fluctuations in Wetting & Drying
Thank You…
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