Plant Illnesses and How to Prepare for Them

Treating plant illnesses doesn't require you to have a doctor's degree. Most plants will give you warning signs so that you can determine what is going on with them.

Once you've determined what is wrong with the plant, you can start treating the problem and getting your plant back to good health. Read on to learn about different plant illnesses and how you can prepare for them and be ready to treat them.

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Plant Illnesses

Any successful gardener is prepared.  It's a good idea to become familiar with the plants you are raising and some of the more common ailments that they can have.  That way, if they do become ill, you have an idea of what you need to do in order to take care of the plant.  Learn some of the common plant illnesses and what you can do to prevent and treat them.

This past spring, I was fortunate enough to attend Crop King's Grower School.  Crop King is a company that specializes in controlled environment agriculture, or greenhouse growing.  This grower's school was an intense two-day workshop that went over different issues that you could have while raising plants.  Although their information was driven toward growing in a greenhouse, the principles can be applied to growing in any situation.

So what can go wrong with my plants?

You provide your plants with nutrient rich soil, water and sunlight.  You're asking me right now "If I'm doing this right, what can go wrong? Aren't plants self-sufficient?".  Well, to a certain extent they are.

Remember, the whole point of being prepared is learning what can go wrong so that you are able to identify and fix the problem.

There are several things that can go wrong with your plants.  Or, I should say, there are things that can affect how well your plant is growing. If you are growing inside, such as in a greenhouse, then your plants can be affected by environmental factors, nutritional and biological factors. If you are growing outside, there are two main areas that can affect your plants- nutritional issues and biological issues (unless you are trying to grow a plant that isn't suited to your environment).

You can then break nutritional and biological issues down even further into four categories.

‚ÄčLet's look at those.

Nutritional Problems

There are two main problems that we can have that are nutritional.  Your plants can have deficiencies or toxicities. A deficiency is defined as a lack of some nutrient.  A toxicity in plants occurs when there is too much of a certain nutrient.

These work in similar ways that they do in humans.  If you don't get enough of a certain vitamin, you can become sick.  That would be a deficiency.

‚ÄčFun fact- An example of this in people would be scurvy.¬† Pirates were notorious for developing scurvy hundreds of years ago.¬† Scurvy is caused by a lack of vitamin C, which is often found in fresh fruit.¬† Pirates that were on ships at sea for months at a time didn't have access to fresh fruit.¬† This led to the development of a vitamin C deficiency, which is commonly called scurvy.

nutrient deficiency in plants, why are my plants turning yellow

Nutrient Issues

Not enough of a nutrient can harm a plant, but so can too much of a nutrient.  Toxicities are most often seen when the farmer puts too much of a fertilizer or nutrient on a plant.  The plant takes in too much of the nutrient, causing the plant to get sick.

You might think that if you apply extra fertilizer that you will see more growth, more fruit or more blooms on your plant, but it (unfortunately!) doesn't work that way.  Make sure that you read the label of the fertilizer or research how much your plants need before you apply.

It's also a good idea to have different fertilizers on hand.  I personally like this liquid fertilizer trio from Fox Farm.  One fertilizer is for leafy growth, one for big blooms and one for healthy fruit.  You simply apply the different fertilizers when the plant is going into the next stage of growth.

‚ÄčTo read more about feeding your plants, check out my article on Feeding Your Plants.

fertilizing your plants to prevent nutrient deficiency

Plant Nutrient Deficiencies

As I mentioned before, plants will often give you signs that they aren't doing well.  When plants have a deficiency, they will usually have stunted growth or discoloration of the leaves.

‚ÄčThe type of discoloration will give you clues as to what type of nutrient the plant is missing.¬† For example, plants that are missing potassium will have leaves that turn dark purple.

what's wrong with my vegetable plants, potassium deficiency in vegetable plant

Plants will show nutrient deficiencies on older leaves first.  Older leaves are leaves that are lower on the plant.  If you notice some of the lower level leaves start to have discoloration, then you may have a deficiency.

Plant Nutrient Toxicities

Toxicity will also cause abnormal growth and leaf discoloration.  Toxicities can also be tricky.  If a plant is taking in too much of a nutrient, then it may cause a second nutrient to not be taken in enough.

A toxicity can cause a deficiency. I know that sounds backwards, but hang with me.

For example, you may have leaves on a tomato plant that start to turn yellow and white.  This could be from a boron toxicity.  Boron is a nutrient that plants require, but remember, too much is just as bad as not enough.   The plant has developed a boron toxicity.  Since the plant is taking in too much boron, it can't take in potassium, so it develops a potassium deficiency.  Now you have two issues that need to be fixed!

‚ÄčFeeding your plants properly is important to make sure that you are taking care of deficiencies without causing toxicities.

fertilizing plants to prevent nutrient deficiency

Feeding your plants properly is extremely important to prevent nutrition related plant illnesses.

Any time that you start growing anew plant, do a little background research and see what that plant wants as far as nutrients.  You want to make sure that your plants are well fed without giving them a toxicity.

Growing native plants on your farm can be an easier option.  Most native plants will only require minimal feeding as they can get most of what they need readily from the soil.

‚ÄčIf you want to go more in-depth about nutrient deficiencies and toxicities and how to identify them, check out this Nutrient Management Article from Montana State University.¬† It's really informative and has excellent information and photos to refer to.¬† And if you have questions after reading it, let me know and I'd be happy to answer them!

Biological Problems

If you have ruled out nutritional problems, you can look at biological problems.  Biological problems can be easier to diagnose as these are often things that you can see.  Yes, you can see discolorations on leaves easily, but sometimes it's harder to break down those colors into an actual diagnosis.

‚ÄčThere are two main types of biological problems- disease and pests.

Disease-Caused Plant Illness

There are countless plant diseases out there.  Some of the most common ones that you should become familiar with include powdery mildew, downy mildew, Botrytis, Pythium and any other disease that might affect the particular plants that you are growing.

downy mildew disease on a vegetable plant, how to prevent disease in vegetable plants

In order to become infested with a disease, the conditions have to be right.  There are three things that a disease needs in order to develop: a pathogen, a conducive environment and a susceptible host.

In order for a disease to develop, there needs to be a pathogen present.  A pathogen is something that causes sickness, such as a bacteria or virus.  This pathogen is what causes the illness.

‚ÄčThe environment also needs to be right in order for the pathogen to reproduce.¬† In other words, the pathogen needs a conducive environment.¬† Many bacteria prefer to grow in warm, humid conditions.¬† If your plant is in those conditions, you may be fighting bacteria more often than you would like.

how to deal with vegetable plant diseases, botrytis on vegetable plants

Lastly, the host has to not only be present, but susceptible.  The host in this case would be your plant.  We know that you have a plant present, or you wouldn't be reading this! So, not only does the host need to be present, but it needs to be in a state that will allow the pathogen to cause illness in that plant.

For example, tomatoes can be infected with Botrytis.  In order for a tomato plant to get Botrytis, it has to have an open wound.  If the Botrytis gets into the open wound of the tomato plant, then it can start to multiply and infect the plant.  Think about when you are pulling sucker stems off of tomatoes.

‚ÄčIf one plant has Botrytis on it and you touch the plant while you are pulling suckers off, then the Botrytis will get on your hand.¬† Then you go to the next plant and pull suckers off of it, creating open wounds with the Botrytis-covered hands.¬† The Botrytis now infects the open wounds on the second plant.

diseases in vegetable plants

Pests That Cause Plant Illnesses

It's extremely important that you are able to identify the pests that could infect your plants.  There are so many pests that it would be difficult to learn them all.  A good idea would be to become familiar with pests that are common in your area and like the types of plants that you will be growing.

Many growers find that it's easier to print out pictures of the pests and label them.  You can laminate and post the pictures up somewhere so that you can see them frequently.  That way, if you see one on your plants, you are familiar with it.

Why do I need to learn which bugs are pests? Bugs are bugs, right?

Wrong!

‚ÄčThere are so many insects out there that are beneficial to your plants.¬† Honey bees and butterflies are some of the more obvious ones.

beneficial insects in the garden, butterfly in the garden

You need to learn which insects are actually harmful to your plants so that you know how to control them.  There are many options for controlling pests.  Many farmers are moving to chemical free options and ditching pesticides.

spraying pesticide on plants

Many pesticides are poison that will kill insects no matter the type.  These pesticides don't affect specific bugs.  In fact, many advertise to do the opposite.  Many pesticide powders claim to kill all kinds of bugs.  The bad thing about that is, not only are they killing the bad insects, they harm, deter or kill the good ones also.

Biological Controls- The Good Guys

Instead of using pesticides, there are many biological controls available that are chemical free.  A biological control is a natural way to get rid of pests.  Biological controls are natural predators or enemies of pests.

‚ÄčAn example of a commonly used biological control is a ladybug.¬† Ladybugs are often used to get rid of aphids.¬† Ladybugs eat aphids like they are candy.¬† If your plants have an aphid infestation, you can purchase ladybugs to put on your plants to eat the aphids.

using beneficial insects to keep pests off of plants, ladybugs eat aphids

Using a biological control can be just as, or more effective than if you use a chemical pesticide.  It does require you to know which pest you have (or at least get close).  If you have a squash bug infestation and you order ladybugs because you think you have aphids, then you're wasting your money.  The ladybugs won't eat the squash bugs.

If you want to order biological controls, you can contact the company that you are purchasing them from.  If it is a good reputable company, they will be able to talk to you over the phone and figure out what pests you have and recommend the proper control.

With that being said, knowing what type of pest you have is definitely helpful.  You can find more information or report diseases or pests to the USDA on the Animal and Plant Health Inspection Service (APHIS) website.

‚ÄčSome plants are naturally less prone to pest problems.¬† Chrysanthemums usually don't have issues with pests or disease.¬† They make a great addition to the landscape that won't attract pests.

Creating a Plan to Treat Plant Illnesses

Now that you know that there are two ways that your plants can become sick, you can begin to form a plan in case illness or health issues occur.

One of the easiest ways that I have been able to drastically reduce pests is through the plasticulture gardening.  Plasticulture gardening is gardening with plastic mulch.  The plastic mulch has many benefits.  One of the major benefits is the reducing of pests.  You can read about how our plasticulture garden performed just three weeks into the growing season.

Sometimes you will see a pest or disease and be able to easily identify it.  Sometimes you won't.  You may have plants that become sick or have health issues without any apparent reason.  You will be able to piece together clues to figure out what is wrong with them.

There may be a disease going around if you notice that neighboring plants are getting sick.  If you pruned your plants and noticed that some of them got sick afterwards, it may be a disease.

If you see discoloration on the leaves of the plants, it may be a fertilizer problem.  You may have applied too much fertilizer or the plants may be lacking a nutrient.  The best bet with fertilizer is to use an all-purpose fertilizer or one that is tailored to your plants.

If you notice eaten leaves or fruits on your plants, you may have a pest.  Or you just may see the pest.  In that case, you need to decide a plan of action.  Identify the pest and determine whether you want to use a biological control.  Biological controls are often more effective and they don't harm the helpful insects.

Create a notebook or binder to help identify plant illnesses.

I recommend creating a notebook with pictures to help yourself identify problems in the garden.  You can put pictures of plants with nutrient deficiencies, toxicities, disease and pests.  It may also be helpful to include pictures of beneficial insects so that you don't mistake the good guys for the bad guys.

‚ÄčIn your notebook, create a general plan of action and instructions for what you plan on doing.¬† If you want to use biological controls for pests, then have a phone number on hand so that you can call the company.¬† I highly recommend calling them and talking to them to make sure that you are buying the correct biological control.¬† It's better to be safe than sorry!
‚Äč
‚Äčūü§öBefore we dive in, I want to give you a FREE guide that will help you grow your best garden yet! Grab your free copy of the From Seed to Supper guide here and grow a bountiful garden this year!

how to prepare for plant illnesses, free vegetable gardening guide

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How do you prepare for plant health issues?  Let me know!

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Founder of Garden. Farm. Thrive.

I'm a multigenerational homesteader, former high school and college agriculture teacher, and your guide for embracing a simpler, more traditional lifestyle. Come along as I teach you how to grow your best garden, raise chickens and other livestock, learn traditional skills and create the homesteading haven of your dreams.

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