10/3/2014

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Identify and Correct Abiotic Disorders in Plugs & Cuttings

Royal D. Heins

Jason TwaddellBall FloraPlant – Selecta Technical Product Rep

jtwaddell@ballhort.com

Abiotic Plant Disorder

• Light

• Temperature

• Water 

• Nutrients

• Gases

Environmental requirements for plant growth

Light

Temperature

Water

Nutrients

Gases

Environmental requirements for plant growth

Any environmental factor can individually or in combination with another factor lead to a problem.

Can be almost an unlimited number of causes.

Examples can be:

Media issues such as improper filling and compaction

Chemicals toxicities such as:

herbicides, 

chlorine, 

insecticides, 

fungicides, 

Growth regulators

etc, applied that are toxic or applied at high rates.

“Critters” such as mice and birds

Seeding too deep or too shallow

Etc.

Physiological issues

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Problem 1

Poor Soil to Stem Contact/Improper Dibble

Some crops require good contact between the base of the stem and the soil to root quickly and uniformly 

Dibble depth and size are often the biggest reasons for this problem but cutting size and uniformity are also factors

Lobelia and calibrachoa require good contact while other genus do not

Improper Dibble Solutions

Know your crop requirements regarding dibble size and depth

Train sticking crews to ensure good soil to stem contact on sensitive crops (lobelia, calibrachoa)

Pinching the top of the soil will secure the stem but may not create good contact at the base where the roots will emerge……be sure that the cutting “bottoms‐out”

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Problem 2

Plants can initiate flowers prematurely when plants in plugs are grown under the incorrect photoperiod.

Examples include Campanula, petunia, and Rudbeckia – Long day plants

And Celosia and Zinnia – Short day plants

Improper photoperiod(Flower on a stick)

Rudbeckia flower on a stick

Celosia Glorious Yellow 11 for 16 photo 16 with early flower set due to normal short days  Celosia Kimono Mix 11‐16‐20 photo 18 with early bud set and late transplant

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Petunia plugs wk 15 with early flowering Petunia with flower on stick week 21

Cosmos initiating flowers early under short days  Zinnia induced under short days flowering small

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Highly Reproductive Petunia Liner

Lobelia with reproductive cuttings

Incorrect Photoperiod…..SolutionsKnow the photoperiodic requirements for crops

Use proper equipment and resources to deliver required photoperiod• This can be as easy as incandescent lighting but be sure to check for necessary intensity

• 10 FC of light or 1 umol are needed at plant level to ensure appropriate night interruption

• For short‐day crops, light from 10pm – 2 am

• Walk crops at night to be sure equipment is working properly and test intensity with a light meter

Communicate with supplier when cuttings arrive already budded or reproductive

Incorrect Photoperiod…..Solutions

For reproductive Lobelia, one needs to re‐vegetate plants before pinching or plants will never branch.

Florel applied 2 or 3 times at 500 to 1000 ppm will typically re‐vegetate a Lobelia.

Plants can then be pinched “high” on the stem to get branching.

Potunia with and without b‐Nine and Florel

Problem 3

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Nutrient Disorder Due to Improper Environment

Boron deficiency in calibrachoa and petunia is common when transpiration rates are low for a period of time

Calcium deficiency can also be a problem during periods of low transpiration

Overall plant growth and nutrient uptake is compromised during poor transpiration periods…..Keep plants active

Distortion and abortion of the growing tip on certain species when water sits on the growing tip for extended time periods, especially at night.

Water on growing tip

Impatiens seedling with water sitting on growing tip Impatiens Super Elfin Lipstick 9 15 for 19 photo 12 plants subirrigated nice

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Impatiens Super Elfin Lipstick 9 15 for 19 photo 12 plants subirrigated nice Impatiens Super Elfin Lipstick 9 15 for 19 photo 12 plants overhead watered with severe tip abortion 

Impatiens Super Elfin Lipstick 9 15 for 19 photo 12 plants overhead watered with severe tip abortion Impatiens Super Elfin Lipstick 9 15 for 19 photo 12 plants on with overhead water with tip abortion with those from subirrigation

Impatiens Super Elfin Lipstick 9 15 for 19 photo 12 plants on left overhead water with tip abortion, right subirrigation gerbera plugs variable and tip distortion week 6

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gerbera plugs variable and tip distortion week 6 Petunia SD Mambo Rose plugs with shoot distortion

Distortion and abortion of the growing tip on certain species when water sits on the growing tip for extended time periods, especially at night.

Plants especially susceptible include Impatiens and Gerbera

Irrigate in the early morning

Horizontal air flow and dehumidification help evaporate water from plants after irrigation.

Under low light and high humidity conditions, blow water off the plants with a leaf blower.

Water on growing tip

Problem 4

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Edema

Caused by imbalance in water uptake versus water lost by the plant

Environmental conditions and moisture management are main factors

High humidity and saturated soils will consistently create problems with susceptible plants

Thunbergia, Ipomoea, Geranium and Cleome are prone to Edema

Edema Prevention

Manage humidity levels in the greenouse

• Keep below 80%

• Purge compartments during high humidity periods

Do not saturate soil on susceptible varieties during cool, cloudy weather

Keep air moving with HAF fans

Problem 5

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Chlorine can cause phytotoxicity to plants.

Sources include sodium hypochlorite and chlorine dioxide

Certain plants such as geranium, Dianthus, dahlia, and pansy are especially sensitive

Chlorine toxicity

Dr. Fisher at the University of Florida recommends that based on his observations that no more than 5 ppm chlorine be injected into any water that is being applied to crops because of the possibility of phytotoxicity from the chlorine or its byproducts.Most typically recommendations are made based on free chlorine at the end of the hose. While this is an important measure to determine if the chlorine has been effective at controlling any pathogens, it is also important that this free or residual chlorine still exists when at most 5 ppm of chlorine has been added to the water.If 5 ppm of chlorine is added to the water and the free chlorine is still less than 1 ppm, it indicates the water needs to be filtered and cleaned to a greater extent before the chlorine is added to the water. So rather than just increasing chlorine concentration, it is important to check whether the incoming water needs filtration or flocculation, or if there is so much biofilm in the lines that it is time to shock-treat the piping for biofilm control.If one is using a 12% sodium hypochlorite stock solution, 5 ppm equals 1

gallon in 24,000 gallons of water. Injection of 4 ppm means one gallon in 30,000 gallons of water.

Chlorine toxicity

Geranium interveinal chlorosis  from chlorine Pansy  with veinal necrosis due to chlorine

Pansy  with veinal necrosis due to chlorine  Dianthus Corona looking ugly  from chlorine

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Dianthus Floral Lace  ugly from chlorine Dahlia with veinal chlorosis from chlorine

Dahlia with veinal chlorosis from chlorine Begonia chlorosis from chlorine

Vegetative Problem 6

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Cycocel Phytotoxicity

• A very common problem in liner production of geraniums and poinsettia

• High rates or high volume applications can cause this reaction

• Be careful not to apply to stressed plants and only spray to glisten foliage, not to run off

Problem 7

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Ethylene damage in shipping

It is common knowledge that geraniums are susceptible to ethylene damage in shipping and this problem occurs every year during the propagation season

Delays in transit, high temperatures during shipping and poor cutting quality can all contribute to this problem

Ethylene Damage…..Solutions

Give ethylene sensitive crops the highest priority when planning production for the week

Be sure to unpack geraniums as soon as they arrive and stick them within 24 hours of arrival

Use of the PGR Fascination can help to minimize the damage but must be used properly

• Keeping it Green…. http://www.ballpublishing.com/GrowerTalks/ViewArticle.aspx?articleid=20454 Lantana shipping damage due to ethylene

Problem 8

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Tip Necrosis on Lantana

• Tip necrosis occurs during shipping process and is related to carbohydrates in the shoot tip and youngest leaves

• Be sure to make lantana a priority in production and stick as soon as possible after arrival

• Tip necrosis seems to be related to time of harvest at the stock farm with best results when harvesting in the afternoon

Lantana with black shoot tips

Problem 9

Flower buds on Alyssum can “lock up” with high rates of paclobutrazol.

“Bud Lock” from Paclobutrazol

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heins@msu.edu ‐ Alyssum with Bonzi drenches left not right Alyssum out of flower from high Bonzi drench 

Alyssum out of flower from high Bonzi drench Alyssum out of flower from high Bonzi drench

Alyssum out of flower from high Bonzi drench Alyssum with small flowers ‐ repeat Bonzi applications (3)

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Problem 10

Rooting Hormone Toxicity

• Foliar application of KIBA rooting hormone will cause the leaves of some plants to curl excessively right after the application

• Plants normally grow out of the phytotoxicity before the liners are ready to ship or transplant

• Excessive stretch can also occur (lobelia in the previous slide)

• Petunia, lobelia and argyranthemum are susceptible

Poinsettia shoot distortion from Dip‐n‐Grow on the growing tip

Lantana Dallas Red with shoot distortion of DipnGrow rooting hormone getting on growing tip 

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Helitrope Marino with  IBA leaf distortion from  Dip n Grow spray 

Rooting Hormone Phytotoxicity Prevention

• Check rates to ensure that you are using the appropriate ppm….. most plants will grow out of the symptoms from an appropriate ppm application

• If using as a dip, only treat the base of the stem and be sure not to let the solution run up the stem and on to the leaves

• Not all plants need hormone for quick and uniform rooting so only use on those crops that will benefit

Problem 11

Leaf Damage Caused by OvermistingMost plants are sensitive to overmisting in propagation and will begin to breakdown if the mist is not properly regulated

Important factors to remember when finding the correct balance of mist

• Duration of mist events and volume of mist applied

• Delay between mist events

• Age of the crop and root development

Properly weaning cuttings off mist is crucial as cuttings start root development

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Poinsettia leaf water soaking and vitrification on cuttings stuck 3 days from excess mist

Problem 12

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Reused plug trays – not properly sterilized between uses.

To date, the only secure way to sterilize plug or liner trays between crops is heat sterilization.

165F for 30 minutes

Experience has shown that it is not a matter of ifbut only when a disease issue will occur if heat sterilization is not applied to re-used trays.

Thielaviopsis or PythiumReused plug trays – not properly sterilized between uses.To date, the only secure way to sterilize plug or liner trays between crops is heat sterilization.

165F for 30 minutesExperience has shown that it is not a matter of if but only when a disease issue will occur if heat sterilization is not applied to re-used trays.

A good clue that trays have not been properly sterilized is presence of algae a few days after seeding.

Thielaviopsis or Pythium

Algae starting to grow from some trays ‐ lack of adequate steaming Algae starting to grow from some trays ‐ lack of adequate steaming (1)

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Petunia plugs ‐ algae right not left from poor sterilization

Some heat sterilization chambers

Boiler and new sterilization chamber for plug trays ‐ Battlefield Heat sterilization room for plug and liner trays under construction ‐Metrolina

Sterilizing trays  ‐Mast Young Plant Liner and plug tray sterilization Catoctin

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Plug stacking for steaming and sterilizing

Problem 13 

Have you seen this before?

The poinsettia liner on the right received the same treatments as the liner on the left

What is causing the clubby root growth?

Shoots and leaves looked fine

Problem 14 

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Mice can cause major damage in a short time

Often most serious in the fall and early winter, especially if there is heavy snow that stays around for several days or more.

Trap, trap, trap and use bait.

Do no wait, damage can be significant in a very short time.

Mouse damage

Mouse damage

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Mouse damage?

Sunflower germination poor due to flats being carried and seed falling out 

Problem 15

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Water and nutrients are two of the biggest and best growth regulators in plug production.

If plants are grown on a bench or floor where the gap between the bottom of the tray and the bench is too short, roots can grow from the plug to the bench and root out gaining additional water and nutrients.

Rooting to the floor

Petunia plug growing very large with roots to floor compared to surrounding plants Petunia plug growing very large with roots to floor compared to surrounding plant

Petunia plug growing very large with roots to floor compared to surrounding plants (4) Petunia plug growing very large with roots to floor compared to surrounding plants

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Water and nutrients are two of the biggest and best growth regulators in plug production.

If plants are grown on a bench or floor where the gap between the bottom of the tray and the bench is too short, roots can grow from the plug to the bench and root out gaining additional water and nutrients.

Solution

Increase distance from plug tray and bench

Rooting to the floor

Celosia plugs 13 for 18 photo 18 under short days  with plants rooting to floor Petunia plugs big from rooting into floor (1)

Petunia plugs big from rooting into floor (2) Petunia plugs rooting to floor below giving variable plants (1)

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Petunia plugs rooting to floor below giving variable plants (2) Zinnia plugs with plants rooting out of bottom of trays

Zinnia plugs with plants rooting out of bottom of trays (3)

Questions???