Unit 2 Plant Health Management

Question 1

Name 4 environmental factors that affect plant growth

Answer 1

The main factors affecting plant growth are temperature, light, relative humidity, soil moisture, and the availability of essential minerals. Natural aging and pest pressure also have an effect on a plant’s condition.

Question 2

Name 2 management practices that may affect plant health

Answer 2

Planting and pruning methods, physical damage, soluble salt concentration, acclimatization to a new site, and chemical exposures affect a plant’s condition.

Question 3

Why are environmental conditions important to plant health?

Answer 3

All plants have environmental requirements and tolerances. Suitable environmental conditions will keep plants healthy and thriving. A healthy plant is less susceptible to pest infestations.

Question 4

What are the raw materials plants use to make food?

Answer 4

Carbon dioxide and water are used to make carbohydrates by photosynthesis.

Question 5

What is the energy source green plants use to produce food?

Answer 5

Photosynthesis is powered by light energy

Question 6

Why do plants need to be acclimated to a new environment?

Answer 6

Plants grown in greenhouses or in the field are adapted to high light levels and frequent watering and fertilization. If they are moved to an interiorscape or to some landscapes, they need to adjust to the new conditions. For example, in the indoor environment, light levels are lower, and plants require less watering and fertilization.

Question 7

Describe the ideal indoor temperature range for tropical plants grown indoors, and explain problems associated with drastic temperature fluctuations.

Answer 7

The ideal temperature range for indoor plants is between 55 - 90 degrees F. Lower temps will result in slower plant growth and chilling injuries. Excessively high temps will result in rapid wilting and utilization of stored food reserves.

Question 8

Describe the function of plant roots

Answer 8

Roots absorb water and minerals. They stabilize the stem, and store moisture and excess food.

Question 9

Why do plants need pore spaces in their growing media?

Answer 9

Roots need the pore spaces to allow water to reach the roots, and to allow gas exchange to take place.

Question 10

Why do plants need fertilizers?

Answer 10

Plants manufacture their own food through the process of photosynthesis. Fertilizers are mineral nutrients which are used by the plant for this process. In some soils and growing media, minerals are lacking or in short supply.

Question 11

What is the difference between a macronutrient and a miconutrient?

Answer 11

Macronutrients are minerals that plants need in fairly large amounts. Plants use micronutrients in relatively smaller quantities. Both are necessary for good nutrition and health.

Question 12

What is “soluble salt buildup”? How does it affect plant health?

Answer 12

Chemical fertilizers, growing media, and water contain soluble salts. These salts build up in the growth media, especially those in of container-grown plants. An excess of soluble salts is toxic to plants. Common symptoms of this problem include leaf tipping or blotching, necrotic spots on leaves, stunted growth, damaged roots, defoliation, and eventually death of the plant.

Question 13

List the steps involved in diagnosing plant problems

Answer 13

1. Identifying the problem symptom
2. Determining the cause or causes
3. Planning a management strategy to solve the problem

Question 14

Describe the 4 perspectives that should be used to detect and describe plant problem symptoms

Answer 14

1. Study the plant from a distance, and note its general condition
2. Make a detailed close inspection of abnormal plant parts and tissues
3. Consult your records or observe the plant over time. Note if the symptoms are recent or if they’ve developed over a long period of time.
4. Call on your previous experiences. Relate this incident to similar situations.

Question 15

Name 2 possible causes of wilted leaves

Answer 15

Lack of soil moisture, excessive heat or a mineral deficiency

Question 16

How can you determine the cause of plant health problems?

Answer 16

Careful observation, studying the symptoms, using tools to monitor environmental and cultural factors, and familiarity with pest biology will help you determine the reasons for a plant’s poor health

Question 17

Why might you want to measure the amount of light a plant is getting? What tool(s) would you use to make this measurement?

Answer 17

Plants need light to produce food. Different plants require different amounts of light. A number of factors affect the amount of light plants get, especially in interiorscapes using only natural lighting. Outdoors, too much or not enough light is not a problem if plants are matched to the site. However, it can be a limiting factor in interiorscapes. Measuring the available light should be done when planning an indoor plant community. These readings should be made during all seasons and weather conditions. After installation, light levels should be checked periodically, because conditions can change. A light meter measures total light intensity. A photometer measures the wavelengths (blue, red and far red) used by green plants.

Question 18

You suspect temperature is causing a plant health problem. How would you take measurements to see if this is true?

Answer 18

Take readings in several locations. in an area of any size, air and soil temperatures may vary considerably. In a landscape bed, shading, mulch color or distance from blacktop or concrete will affect temperature. You should measure temps at different times. Indoors and out, temps fluctuate on a daily and seasonal cycles. You can use thermometers to measure temps. High-low thermometers record temp extremes. A thermograph will make a complete record of temps over time.

Question 19

You suspect the chemical makeup of a growing medium is no longer suitable for the plants rooted in it. What should you do to confirm your suscpicions?

Answer 19

You must first know the mineral and pH requirements of the plants. Then you can use litmus paper or a pH meter to measure soil pH. A solubridge (conductivity meter) measures soluble salt content. You may see a ‘crust’ of salt buildup You will get a more complete picture of soil conditions from a soil test. A routine soil test done at Virginia Tech will measure the pH and mineral content. The report will include a recommendation based on the type(s) of plants you’re growing. Special tests will measure soluble salt level and/or organic matter content.

Question 20

Name 2 tools used to monitor plant pests

Answer 20

Traps for flying insects, hand lenses (for close inspection of plants and plant parts, looking for insects, mites, nematodes, fungal strands or fruiting bodies, and other evidence of a pest’s presence) and binoculars to examine the crown of a tree.

Question 21

Why might you want to measure the moisture content in the air? What instrument would you use?

Answer 21

Adequate air moisture is important to the general health of the plants. A hygrometer measures relative humidity.

Question 22

Why do you need to continue monitoring a plant after you take action to solve a health problem?

Answer 22

You should monitor the plant if and how it is responding to the treatment. If the plant is not responding as expected, the management plan may need to be changed.