Dealing with Spider Mites Infestations

by Richard Chew




It is interesting to see that there are more interest in my postings on dealing with diseases and types of horticultural oil for pest control in my blog than my postings on feeding.


I thought my readers would be interested to know my approach in dealing with spider mites.









Incidentally 'The Prince' rose got infected with spider mites after I placed it at location where it received direct late morning/noon sun for about a week.

My immediate response was to jet spray the underside of the leaves to remove the mites.









However the next day, the mites came back again, it was like Houdini magic, appearing out of nowhere.






Upon checking AccuWeather (example report below), I learned that the sun was very intensed on that week when my rose plant got infected.


Just to give you an idea on understanding the report below. UV Index as indicated below in the report is the measurement of UV light intensity. At the time of writing this posting, it was measured at 3 (moderate) . If UV index is anything below 5, it is fine for most plants. If it exceeds 5 for few days consecutively, it can be hazardous to the leaves.








I extracted the definition of UV Index below.

UV Index is the Ultra Violet Radiation Index. The index is a value between 0
(none) and 15 (extreme). This value shows the part of the invisible spectrum of
light that reaches the earth from the sun. Although the Earth's atmosphere
protects us from the bulk of these rays, those that get through are still
harmful. UV has been linked to sunburn, skin cancer, skin wrinkling and aging,
cataracts, and other ocular damage.

Accuweather is a very useful tool for me to monitor the amount of rain, sun and weather condition in my garden, when I am away from home.


I checked the leaves and noticed speckled marks/textures were more distinct than it was before. This was a clear sign that it had been too exposed to intensed sunlight. Accuweather UV Index indicated level 8 which is considered harmful.


This was not the only rose plant with speckled leaves in my garden, I suppose this rose type, being less tolerant to sun, makes it more vulnerable to infestation compare to those originated from tropical climates.







The picture below is taken from the lower leave. I suppose this leave is more shielded from direct sun compare to the ones above.










Another observation, the silk-like webs and presence of spider mites tends to appear on the top of the plants where it receives most exposure to sun/heat. Very seldom we will find spider mites and web nesting at lower shielded part of the plant.


I believe spider mites thrive on leaves that are most 'cooked' by the sun and are attracted to most "litup" leaves (at upper part of the plant). The baby spider mites feed on simplified sugar 'cooked' by the sun/heat because it is easily consumed. Removing these leaves, may cause these spider mites to move their breeding ground to lower leaves. By retaining the infected leaves, in a way the mites are "contained".


The green in the leaves, suggests the presence of chlorophyl and that the leaves are still capable of manufacturing sugar. Unfortunately major portion of the food produced are consumed by these spider mites. But on the positive note, it discourages mites from moving to other leaves as food is easily accessible at current nesting place.


Pesticide is necessary, especially if regular jet water spray didn't work or you knew the rose plant was not in good health prior to infection, perhaps due to lack of feeding or water or lack of essential factors. In this situation pesticide helps to manage damage control but not neccessarily provide full aid to recovery.


To achieve full recovery, contrary to what we learn and know, the best way to fight against these pest, is actually a passive and indirect one.


Unlike humans and animals, plants do not have similar repair capabilities or immune system to heal itself. Plants heals by regrowth.




If you are reading this and are encountering recurring spider mites problem, perhaps you should consider nursing your rose plant to inbuild a stronger line of defence.



The following are some of the things that I did to 'The Prince'. These steps mentioned here is not a formula or technique that will solve all spider mites problems. The objective is to repel mites & nurse the plant back to health.

1. Foliar Feed - I used seaweed extract, and spray about 3 to 5 times a week, depending on the severity of infestation.
2. Relocate rose plant away from direct sun
3. Use only organic fertilizer - I also include seaweed extract to moist the top soil after watering
4. Jet spray with water regularly the underside of leaves - especially when the mites are visible
5. Place large slices of garlic above the soil - it seemed the pungent smell of garlic repels the mites

Below are pictures of new growth.

I noticed some dramatic improvements after relocating the rose plant and carrying out the exercise above regularly. The mites were less visible the following day. However the mites emerged on 3 days later with webs at the top of the plant. I continued the jet spray and foliar feed. It is now day 8 since I first detected the spider mites. And there is no recurrence since I last jet spray 3 days ago. I won't say that it has completely recover from the spider mites because there could be small ones that are not visible to the naked eye.

From this case it is quite evident that the population of the mites is pretty much controlled. As long as there is new growth, new leaves, the rose plant is on the road to full recovery.

Spider mites are small, 8 legged, spider-like creatures which
thrive in hot, dry conditions (like heated houses). Spider mites feed with piercing mouth parts, which cause plants to appear yellow and stippled. Leaf drop and plant death can occur with heavy infestations. Spider mites can multiply quickly, as a female can lay up to 200 eggs in a life span of 30 days. They also produce a web which can cover infested leaves and flowers.

I believe when there is no recurrence of spider mites in 30 days, we can breath a big sigh of relief.

Operation Recovery - Hybrid Rose - Part 2

by Richard Chew

This is continuation of my last post in Dec.

http://rosegrowing.blogspot.com/2008/12/operation-recovery-hybrid-rose.html

In case you are wondering what happened to this rose. It didn't get through.

It deteriorated very quickly when I applied my home-made aerated compost tea.

I learned that feeding needs changes when the rose plant become more established. I believe the soil was too acidic, if it was less acidic the recovery would have been quicker. And also by adding the compost tea, I probably introduced unfavourable soil organism into the soil, thus affected the roots.

Journal of my Constance Spry

by Richard Chew

This is my recent added collection in my garden. This is my 2nd attempt to grow this rose.

Basing on its shrub size, fragrance and flower characteristic, this rose is very similar to Constance Spry.

Constance Spry is bred by David Austin, a very popular English Rose. This was his first breed.

It can grow up to 8 feet high.

It has strong Myrh fragrance, similar to Winter Warmer's English Rose Tea and Lovely Lace Perfume Oil's Tea Rose Fragrance.

I hope to grow this rose to a reasonable size, hopefully the blooms will be profused enough to fragrant my garden.

It is a big dream, I hope to get this right.

I will post my journal of growing this rose in my blog.

Acid or Alkaline? What pH means in gardenspeak

I found this resource that explains about acidity of soil.



http://www.plantea.com/pH.htm





Acid or Alkaline? What pH means in gardenspeak


By Marion Owen, Fearless Weeder for PlanTea, Inc. and Co-author of Chicken Soup for the Gardener's Soul

Did you know that beer, Swiss cheese and soil are all related?

That's right. They are kissing cousins. The pH of things is one of the mysteries of daily life. It comes up when the conversation turns to beer making, swimming pool water, dairy products or garden soil. This degree of acidity or alkalinity, is expressed as a number is called pH. What's really being measured is the concentration of hydrogen (H) ions -- the more hydrogen ions there are, the more acid the thing being measured is.

If it sounds like a foreign language, don't worry. Fortunately, a clever scientist developed the pH scale. It runs from 0 to 14, where neutral is right in the middle at 7.0. Less than 7.0 is acidic (sour) and more is alkaline (sweet). Lemon juice, for example, has a low pH of 2.0 while baking soda measures a high 8.5. Take a look at the scale below to see pH values for common items:





How the pH scale worksLike the Richter scale that's used to rate earthquakes, the pH scale is not linear. The intervals between numbers is logarithmic, which means every number on the scale shows ten times less H concentration than the number below. Soil with a 5 is ten times more acidic than soil with a pH of 6.

What pH means to you, the gardener

Did you get all that? Don't worry. Let's take a look at pH from a practical gardening standpoint. Remember, below 7 is acidic; above 7 is alkaline. The good news is that most home garden plants prefer soil that's a little on the acidic side, around 6.5. Exceptions include potatoes and rhododendrons, which thrive in 5 or 5.5, and many desert plants that grow well in soil having a pH of up to 8.0. (See chart below). Thankfully, plants are usually pretty forgiving and will be happy as long as the reading is close. But some plants do have more specific requirements.

Why is pH is so important in gardening? Because soil acidity or alkalinity directly affects plant growth. If a soil is too sour or too sweet, plants cannot take up nutrients like nitrogen (N), phosphorus (P) and potassium (K). And plants need specific amounts of those compounds--just like we need proteins, carbohydrates and vitamins to grow--to thrive and fight off disease and stress. Let's look at it another way...

Nutrient uptake and pH

Have you ever been disappointed with the performance of your vegetables or flowers, even though you gave them the best care you could? Truth is, pH might have been the problem. Plant roots absorb minerals such as nitrogen and iron only when they are dissolved in water. Now if this soil "soup" solution (the mixture of water and nutrients in the soil) is too acid or alkaline, some nutrients won't be dissolved, and as a result, they are unavailable to plants. They are said to be "locked up."

To put it another way, if the pH isn’t close to what these plants require, some nutrients, such as phosphorus, calcium and magnesium, can’t be dissolved in water. And since plants drink their food instead of eating it, if the nutrients aren’t dissolved first, the plant can’t absorb them. Thus, your corn, lettuce, roses and geraniums won't grow or produce to their full potential.

Most nutrients that plants need are readily available when the pH of the soil solution ranges from 6.0 to 7.5.
Below a pH of 6.0 (acid): Some nutrients such as nitrogen, phosphorus, and potassium are less available.
Above a pH of 7.5 (very alkaline): Iron, manganese, and phosphorus are less available.


Why soil pH varies so much

I wish I could snap my fingers and tell you that if you live in a certain area of the country you have a specific pH. But soil pH can vary from one side of the street to the other. What's more, we also learned that different plants require different pH levels.

Many environmental factors, including amount of rainfall, vegetation type and temperature can affect soil pH. Here are some general guidelines:
Areas with heavy rainfall and forest cover have moderately acid soils.
Soil in regions with light rainfall and prairie cover tend to be near neutral.
Areas of drought and desert conditions tend to have alkaline soils.

The pH of cultivated and developed soils often differ from that of native soil. During construction, for example, the topsoil may be removed and replaced by a different type. Hence, your garden soil pH could be very different from your neighbor's.
Having said all this, please don't get fixated over perfect pH and dump a bunch of lime in your garden to sweeten the soil. Let's take it step by step...

How to correct pH in soil

As the saying goes, "To know where you are going, you first have to know where you are." Thus, when changing the pH of soil, the first thing you need to do is test your soil. Test it at home using a do-it-yourself kit or with a portable soil probe/pH meter. You can also send a sample to a lab for a more in-depth analysis. Sending your sample away to a private lab will give you the most complete analysis, although it's more expensive than sending it to your local extension service.

"The soil is not, as many suppose, a dead, inert substance. It is very much
alive and dynamic. " -- J.I. Rodale, "Pay Dirt" (1898-1971)

Soil can be brought back into balance fairly quickly if they are not too far out of the ideal pH range of 6.5 to 7.0. You can make adjustments by applying soil amendments such as dolomite limestone or gypsum. The best way to make pH adjustments is to incorporate compost and mulch. There are dozens of materials that you can compost. Adding organic matter to the soil also tends to make both acid and alkaline soils more neutral. On the other hand, applying chemical fertilizers makes soil more acidic.

To RAISE the soil pH(Translation: If you have acidic soil)

If your soil is too acid, you need to add alkaline material. The most common "liming" material is ground limestone. Ground limestone breaks down slowly, but it does not burn plants like "quick lime" does. Apply it to the garden and lawn in the fall to allow time for it to act on soil pH before the next growing season. A rule of thumb for slightly acid soils: apply 5 pounds of lime per 100 square feet (say a 5 x 20-foot raised bed) to raise the pH by one point.

Apply limestone: 5 pounds per 100 square feet

Applying wood ashes also will raise soil pH. Wood ashes contain up to 70 percent calcium carbonate, as well as potassium, phosphorus, and many trace elements. Because it is powdery, wood ash is a fast-acting liming material. Be careful, a little goes a long way. Limit your application to 2 pounds per 100 square feet and only apply it every other year in a particular area.


To LOWER the soil pH(Translation: If your soil is too alkaline)

In this case, you need to add a source of acid. Options include pine needles, shredded leaves, sulfur, sawdust and peat moss. Pine needles are a good source of acid and mulch. Peat moss with a pH of 3.0 is often recommended as a soil additive. Before you use it though, consider the other options, because peat moss is nutrient-poor, expensive, and it's a nonrenewable resource.
So the next time you jump in a pool or sip on a glass of wine, you can relax, knowing that all things are connected -- many of them by pH!!!

The Plant Doctor - Plant Disease and Fertilization [EXT]

This is good resource to explain fertilizing to resist diseases.

Found this resource from this link http://msucares.com/pubs/infosheets/is1668.pdf


By Dr. Alan Henn

The Plant Doctor - Plant Disease and Fertilization

Plants must have a proper growing medium for healthy growth. Most often the growing medium is soil. To support healthy plant growth, soil must have the moisture, structure, pH, mix of organic matter, and available nutrients to meet the plant’s needs. A fertile soil is a well-blended mix of these. When any of these components is damaged or falls out of correct proportion, plant growth is affected. Most common problems result from imbalances in nutritional elements or improper pH.

Sixteen nutrients are essential to plant growth. They are designated as either macro or micronutrients, depending on the amount required for good plant growth. Three of the macronutrients, carbon, hydrogen, and oxygen, come from air and water. The other six, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur, come from the soil. Macronutrients are frequently called major elements because plants need lots of them. Micronutrients, often called minor elements, include iron, manganese, zinc, copper, boron, molybdenum and chlorine.

They come from the soil. Although plants need only small amounts of micronutrients, the micronutrients are as essential for plant growth as macronutrients. A plant may also absorb nonessential minerals. Some of these may be toxic to it or to animals that may eat the plant. The availability of many essential elements depends on soil pH. Lower-thannormal amounts of nutrients generally reduce growth and yield (flower or seed) of the plant. When the deficiency reaches a certain level, the plant develops acute (sudden) or chronic (over a period of time) symptoms. Deficient plants are susceptible to diseases.

Symptoms produced by deficiency of an element depend upon that element’s role in plant growth. Usually, a deficiency produces several different symptoms. Some deficiencies produce similar symptoms; the combination of symptoms produced is unique but sometimes hard to notice. Many nutritional imbalances produce symptoms similar to those caused by pathogens, and the two problems are often confused. The balance of a nutrient in relation to other nutrients influences disease development. Plants with balanced fertility are less susceptible to diseases, but plants with imbalanced nutrition may be predisposed to attacks by pathogenic organisms such as fungi or bacteria. We know more about the influence of nitrogen on the development of diseases than we know about the influence of other elements. Too much nitrogen often causes more severe disease. For example, rice stem rot, verticillium and fusarium wilt of cotton and other plants, powdery mildew on small grains, cereal rusts, fire blight of apples and pears, and boll rot of cotton may be more damaging if you apply too much nitrogen.

Susceptibility and incidence to grey mold and myrothecium incidence increase with increasing nitrogen in some greenhouse plants. On the other hand, Rust on perennial ryegrass is lower when plants are grown under high nitrogen fertilization. It is not just the amount of nitrogen that is important; its form is also important, either nitrate or ammonium. One disease (foliar, wilts, or root rots) may be made worse by ammonium nitrogen, but another may be made worse by nitrate nitrogen.

Nitrogen levels should be balanced with potassium, since disease susceptibility generally increases with higher nitrogen-to-potassium ratios. Some diseases that are made worse by too much nitrogen may at least be partially reduced by increasing potassium. This is true in grey mold in tomato and in some bacterial stem rot. Likewise, Melting out, Leaf spot, Pythium blight, and Sclerotina dollar spot are greater under high nitrogen fertility. This effect can be offset for all but Sclerotina dollar spot by increasing phosphorus and potassium levels, bringing the fertility level more in balance.

As you can see, phosphorus and potassium fertilization must be kept in balance with nitrogen for the crop concerned. Deficient potassium levels play a major role in some diseases. Leaf lesion and root and crown rot caused by Bipolaris and Bermudagrass decline caused by Gaeumannomyces are worse in potassium deficient soils. Bermudagrass with a history of spring dead spot should be watched for potassium deficiencies so corrections can be made immediately. Adding phosphorus and potassium to the soil may even increase resistance to bacterial blight of cotton and cereal rusts.

Calcium enhances resistance to many diseases by hardening cell walls. Adequate calcium will increase resistance to bacterial blight in cotton and to bacterial spot on peaches and plums. Adequate calcium fertilization in wheat will reduce the amount of seedling blight from Helminthosporium.

Calcium-deficient plants are more susceptible to infection by various pathogenic fungi such as Pythium blight and Fusarium blight.

Calcium deficiencies, along with low or changing soil moisture, can cause blossom end rot of tomatoes and peppers.

Zinc deficiency is called Rosette on pecan trees and Little-leaf on peaches and apples. Boron can cause abnormalities of plants when in excess or when deficient.

Boron deficiency can cause black heart disease in sugar beets. Turfgrass diseases are most influenced by calcium, nitrogen, potassium, and phosphorus. This is particularly true in sand-based greens.

Extremely alkaline soils may not be able to furnish one or more micronutrients. Iron, zinc, and manganese eficiencies often occur in alkaline soils. The severity of the condition will depend on the plant species and weather conditions. Iron chlorosis (yellowing) is a common nutritional problem in Mississippi. It is usually brought on by high soil pH. Plants afflicted with iron chlorosis often suffer from various leaf spot pathogens. Other diseases made worse by alkaline soils include soil pox or soil rot of sweet potatoes. Similarly, Irish potatoes will have no scab in soil with pH 5.2 or lower. Scab may become more prevalent as the pH increases. Adding acidifying material, such as sulfur, may help improve these conditions. On the other hand, Bermudagrass decline is worse in high pH rather than low pH. Too much salt in the soil water may damage plants. The salts may concentrate from over fertilization or from chemical salts naturally occurring in the soil or water. The appearance of most plants grown in salty soils will be similar to plants grown on extremely dry soils. The plant will be stunted, leaves will be yellow, and they will often show dead tissue along the leaf margins and at the tips.

Soil organic matter furnishes nutrients for microorganisms and for the plant growth. Organic matter improves the water infiltration and retention in the soil, enabling it to retain water and air in desirable proportions. It may inhibit certain pathogenic organisms, but other pathogens may flourish. Disease will sometimes develop more where there is a lot of organic matter. Some diseases, such as verticillium wilt on cotton, thrive in wet soils that have had high applications of organic residues.

There is no general rule for using fertilizer to avoid plant diseases. You must consider each disease separately and manage fertility to fit the situation. The best practice is to assure enough of the nutrients and appropriate soil pH for the plant. You can know the correct adjustments to make by taking a soil sample and following the recommendations. Recommendations are based on many factors, including plant disease threats, and research is continuing to uncover more about specific fertilizer practices for disease control.

Some common symptoms of
nutrient deficiencies in Mississippi

Nitrogen: Leaves are light green and lower leaves turn
yellow or light brown. Stems may be thin and shortened.

Phosphorus: Leaves have a purple tint or are bluish green.
Lower leaves may turn light brown. Stems may be thin
and shortened.

Potassium: Thin stems, which may die-back in severe
shortages. Older leaves may yellow, and the margins and
tips may brown.

Calcium: New leaves are distorted with curled margins.
They may have brown spotting.

Iron: Young leaves are yellow between the veins, but the
veins remain dark green. Sometimes brown spots appear.

Copyright 2004 by Mississippi State University. All rights reserved. This publication may be copied and distributed without alteration for nonprofit educational purposes provided that credit is given to the Mississippi State University Extension Service.

By Dr. Alan Henn, Associate Extension Professor, Entomology and Plant Pathology
Discrimination based upon race, color, religion, sex, national origin, age, disability, or veteran’s status is a violation of federal and state law and MSU policy and will not be tolerated. Discrimination based upon sexual orientation or group affiliation is a violation of MSU policy and will not be tolerated.

Information Sheet 1668
Extension Service of Mississippi State University, cooperating with U.S. Department of Agriculture. Published in furtherance of Acts of Congress, May 8 and June 30, 1914. VANCE H. WATSON, Director (POD rev-10-07)