Floriculture 2.1

Disorders and Deficiencies

Cold temp (Freeze)

-Occurs when temp goes below 32˚F

-there does not have to be frost for damage to happen

• damage happens at the cellular level when plant tissue freezes

• the cell within the plant will freeze and may burst the cell wall causing cellar death

• the severity of the damage depends on how quickly the temp drops and how long it stay below freezing as well as the health and maturity of the plant

  -young plants are more susceptible

• symptoms leaves limp and dry / doesn’t show up overnight

• Prevention (if in non temp controlled environment)

  -eliminate nitrogen fertilizer use

  -ensure all plants are healthy and mature by the end of fall

  -reduce water frequency when approaching winter

  -cover young plants with a blanket when temps drop

• Treatment

  -chemically no treatment listed

  -culturally correct / adjust temp

Cold Water Damage

-Cold water temps can harm a plant, causing stress and chilling injury

-water below 41˚F or 5˚F is too cold

• Symptoms signs can be seen on leaves as lesions or ring spots, the affected leaves turn white and necrotic, and the cause can be easily mistaken as a viral disease

• Prevention

  -use water that is room temp

  -avoid watering leaves, just the growing media

• Treatment

  -no chemical treatment

  -culturally correct watering method and temp

Ethylene Damage

-ethylene is a hormone found in plants that initiates flowering, fruit ripening and seed germination.

-its normally used in greenhouses but if improperly ventilated it can cause harm to plants / over exposure causes damage to flowers and flower buds

• Symptoms

  -over exposure causes flowers and buds to abcise/fall off

  -leaves will epinasty / drop

  -extent of the damage depends on the sensitivity of the plant

• Prevention

  -Proper use and maintenance of heating units

  -when using equipment that uses propane or combustion engine area must be well ventilated

  -clean up all dying or damaged plant material

• Treatment

  -chemically (none)

  -culturally - reduce relative humidity

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.Insufficient Water Damage

-too much water to a plant causes drowning because the roots can’t receive oxygen

-not enough water causes dehydration

• Symptoms

  -underwatering causes leaves to wilt and discolor to yellow or brown. also outer edges of the leaves curl inward and feel dry and crispy

  -overwatering causes water pressure to build up in the cells creating edema (blisters) and the leaves will be soft and limp

• Prevention

  -use moisture meter

• Treatment

  -chemically (none)

  -culturally - correct watering

Iron Deficiency

-iron is the most important of the micronutrients required in plant growth but less is needed than macronutrients

-Iron can be found in growing media with a pH below 6; the more alkaline, the less iron

-plants use iron for the formation of enzymes and chlorophyll / green color

• Symptoms

  -yellowing of leaves this is called iron chlorosis and it makes younger leaves appear yellow with green veins.

  -when a plant is over watered it is harder for it to absorb Iron in the soil.

• Prevention

  -allow time between watering for the soil to dry out preventing root stress and damage

  -if soil pH is 6.5 or higher the iron is unavailable to the plant

• Treatment

  -apply complete fertilizer. used acidic fertilizer to lower the pH

Nitrogen Deficiency

-Nitrogen is the most important macronutrient, its required in large amounts

-its a essential element in amino acids and is a component of nucleic acid which helps make DNA

-when levels are low if affects the development of chlorophyll and the photosynthesis process

-nitrogen is absorbed through the roots so the growing medium will have a lot to do with a plant’s nitrogen levels

• Symptoms

  -leached or volatile soils are signs of low nitrogen content.

  -the plant shows a yellowing of older leaves and an overall lightened color in the plant

• Prevention

  -use slow-release fertilizer to prevent leaching

  -inject water-soluble nitrogen into irrigation water

  -send in soil samples for nutrient analysis

• Treatment

  -chemically none

  -culturally apply complete fertilizer. use fertilizer with high levels of nitrogen (ammonium, nitrate or urea)

Phosphorous Deficiency

-phosphorus is a unique and important macronutrient

-it helps regulate growth by being a part of respiration, photosynthesis and reproduction

-the function of phosphorus cannot be replicated by other nutrients so a deficiency is very damaging

• Symptoms

  -leaves are unable to grow to their normal size and turn dark green with the edges turning a dark purple/red color

  -caused by a build up of carbohydrates not being utilized by phosphorus

  -root mass is decreased which makes the plant less able to absorb things like water and nutrients

• Prevention

  -send in soil samples for nutrient analysis

  -test pH level in soil. phosphorus is most available in the 6-7 range

• Treatment

  -chemically none

  -culturally - apply complete fertilizer. use fertilizer with high levels of phosphorus (phosphate)