Simple tips for keeping diseases at bay

Every year, gardeners lose produce, sleep, hair and have their general happiness eroded through the onslaught of a range of diseases that sicken their plants and undermine their efforts to create a beautiful and productive yard and garden.

When it comes to diseases, there are three basic requirements in order for disease to occur.  Without all three, you won't get disease.  The level of each combines to create the overall severity of the disease.  The first is a susceptible host.  The second is a pathogen.  The third are conditions that favour the development of the disease.

While you can’t always fix every problem, there are a few things that you can do to try and minimize the impact due to disease.

• Start clean – It is critical to start with the best plant material that you can.  Just because something is cheap doesn’t mean you should purchase and plant it.  Select plants that are healthy, free from disease, and that are actively growing (if that is what you want).  At the same time, make sure that the location that you have selected is good enough to give the plants a chance to get established and give them a head start on any attackers.  The same conditions will help the plant stay ahead of any attacks (hopefully). 
•  Accept defeat (temporarily) – Some diseases will come back year after year and some diseases have very specific hosts.  If you get a disease that needs a certain host, consider not growing that plant for a couple of years, or if you have the space, don’t plant in that location.  It might mean sacrificing the taste of a favourite veggie for a short time, but in the long run, breaking the disease cycle will hopefully mean fewer headaches in the long run. 
• Don’t over water or overfeed – It is possible to kill with kindness, especially in the garden.  Don’t succumb to the temptation to keep throwing water and fertilizer at the plants. Healthy plants are more resistant to disease (generally), whereas plant gluttons are lush, soft and overgrown: a.k.a. easy targets. 
• Drainage – Plants generally aren’t adapted to growing in water and react accordingly when subjected to saturated or overly moist conditions.  Too much water will usually result in poor, weak growth and an increase in both root rots and other diseases.  Over watering can actually look like the early stages of drought stress, but there is no nighttime recovery or positive response to adding more water. 
•  Let the air flow – Stagnant air or poor air flow results in higher humidity and the potential for more foliar diseases.  Don’t put plants too close together, either in beds, between or within rows.  Ensure that perennials are pruned properly and don’t create a completely enclosed, over-sheltered environment. 
• Encourage drying – Most diseases thrive in moist conditions.  The longer leaves and plants stay wet, the easier and more quickly diseases can develop.  Consider watering in the morning, when plants will dry out more quickly.  Consider watering the soil surface, not the foliage. 
•  Notice and rogue (remove) the rogues – If something looks weird or abnormal, take a closer look and see what is going on.  Consider taking anything that is abnormal OUT, in case it spreads to other plants. 
•  Remove and bury – Another way to break the disease cycle it to get rid of infected material.  If something is aggressively moving through a planting, do your best to contain it.  When the season is done, encourage a rapid breakdown of the diseased material by burying it or removing it entirely from the site.

These few steps can help keep the diseases at bay and maybe cut down on the mental trauma that can come from gardening.  Good luck.

Meadow Spittle Bugs

There are literally thousands of things that surround us on a daily basis that we walk past without a second glance (or often even a first one).  However, if something is brought to our attention, we tend to notice them over and over, even if we’ve never seen them before.

Many insect and diseases are like that.  One afternoon last week, I got an email from someone asking if I knew if people were noticing a particular pest in their strawberries.  It is a very minor pest, which I’d heard of but had never set eyes on before.  Imagine my surprise (and delight, I will admit to it) when the very next morning, as I was weeding my flower bed, I came across this very insect.  Within an hour, I found it again and again in my strawberries.  It makes picking strawberries that much more interesting, since I am “eager” (yeah, I’ll admit to that), in a weird way, to find this little critter again.

Spittle mass on Creeping Bellflower (weed)

So, let me share with you this little insect that is the “proud” possessor of a fairly disgusting reputation but is, in fact, pretty fascinating.  The insect that I am referring to is the Meadow Spittle Bug.

The Meadow Spittle Bug (Philaenus spumarius) is found a number of different host plants, such as strawberry, clover, alfalfa, a number of grasses, various weeds and some ornamental plant species and is generally considered to be a minor nuisance pest in Alberta.  It is lists about 400 plant species as hosts and is considered to be a general feeder.  It can be damaging in some regions and on some crops, but not on the Canadian Prairies.

Most likely you’ll find (and recognize) MSB more by touch than sight most of the time and, odds are, MSB will be there but you won’t see it.

Frothy spittle "gift"

The first (and predominant) sign of spittle bugs is a subtle-ish frothy or foam mass on the stems, leaves, or perhaps the fruit of the host plant.  Spittle masses can range in size, but are often upwards of ½ an inch or more in diameter.  In my experience, masses can be found pretty much anywhere in the plant canopy but are most often in the lower parts of the canopy.  As you move strawberry leaves aside to find and pick the fruit, you’ll get a wet/slimy feeling and find your fingers with a bit of wetness or foam on them.  Not overly pleasant, but bearable.  You might also catch a glimpse of a mass on an upper leaf surface.

Spittle mass on upper leaf surface of a strawberry

Closer view of spittle bug mass - note individual bubbles

Spittle bugs feed by piercing and sucking.  MSBs don’t tend to cause yellowing, but if there are lots and lots of spittle bugs on the plant, you might see some stunting or perhaps wilting of the plant.

MSBs look a bit like large aphids (a bit egg or pear-shaped), but adults are mottled and winged and can hop and fly (aphids just sort of mosey slowly or park, for the most part).  They are approximately 7 mm in length.  The nymphs are what you will find inside the spittle mass.  They range from orange-yellow to green (depending on the instar (growth stage)) and can stay inside the masses for up to a month while they mature.  Unlike aphids, they can really move when they are motivated.

Spittle bug nymph (probably later instar)

Spittle bug nymph (side view)

MSBs overwinter as egg masses that are laid on lower plant parts.  Nymphs hatch and emerge in late spring.  Once the nymphs hatch they start feeding and produce a frothy mass of little bubbles.  After close examination, I can safely say that they essentially blow the bubbles out of their nether regions, which extends to look a little like a short elephant trunk that waves back and forth, side to side, depositing a bubble one at a time.  In a short time (2-3 minutes), they can produce enough bubbles to equal half their body size.  The spittle masses protect the MSB nymphs from predators and desiccation.

Meadow Spittle Bug nymph - note the slightly distended rear end (where the bubbles come from)

Spittle bug nymph blowing bubbles out of its nether regions

Some sources lead me to believe that spittle bugs are more of an issue in humid regions, which would suggest that MSB might be more of an issue in more humid years.  It certainly jives with the tendency of the MSBs to put their spittle masses in the lower canopy, where the humidity is higher.

While the MSB is gross (people hate to put a hand in the masses), it generally doesn’t merit any sort of control measures.  Weedy areas/fields tend to have more MSBs, so controlling weeds can cut down on hosts and keep populations to a minimum.  Chemical applications (if they are made) for other pests may coincidentally control the MSB, however the spittle masses also protect the nymphs for the most part.

While I am not an “insect guy”, you have to admit that insects can be pretty interesting.  So, keep an eye open.

Dealing with insects in the garden

There are literally hundreds or thousands of different insects that find their way in and through our gardens every year.  Some are there all the time, some just come and go.  Most are harmless to you and your plants and lots are even helpful.  Encouraging them is worth the effort.  Some insects (the pests) are annoying.  Some are destructive and have a significant impact.  Managing them is a challenge.  Regardless, we first have to accept that insects are there (whether we like it or not) and from there we can move to minimizing the impact of the pests.

What follows is a brief and simplified list of some the things that you might consider doing (alone or in combination) to minimize the overall impact of pests, by reducing or preventing infestations and making things less “pest-friendly”.

• Start clean – Insect pests can, and will, arrive under their own power.  Some walk.  Some crawl.  Lots fly.  Others catch a ride.  However, bringing them into your garden seems a bit foolish and is a bit like tempting fate.  It is kind of like saying “They probably won’t like it here”.  Therefore, the strategy is to ensure that any plants that you introduce to your garden are free from insects or other pests.  Give the plants you are buying a good once-over and pick those without any stowaways.  Also, make sure that any plant material that you plant is healthy, so they have a good head start on life. 

•  Know your friends – There are many (a huge number) beneficial insects running, flying or crawling through the garden.  Try to understand what the insects that are present are doing.  Recognize the insects that that aren’t doing any damage or that might be helping out.  Just because it is on the plant, doesn’t mean it is hurting it.  Some good insects may resemble the bad ones, but you can often tell friend from foe using the statement in the Bible that said “Wherefore by their fruits, ye shall know them.”  Watch what they are doing. You’ll see the clues.

• Know (and understand) your foe – Just like knowing your friends is important, you have to be aware of the different pests that can damage your plants (a.k.a. your enemies).  Know that what they and their damage looks like, as well as a bit about their life cycle.  This way, you can know whether you have a problem or not and how best to minimize their impact.  The idea is to know what their Achilles heel is and where to hit them.  By knowing how they move, how they overwinter, how they reproduce, if they need specific hosts, what climatic conditions they prefer, you’ll be better equipped to counter them.

• Encourage rivalries – Once you know friend from foe, you should consider encouraging and/or introducing beneficial insects as a way to manage the problem insects.  You can do this by being judicious in your pesticide applications, planting species that serve as a “home” for the beneficial insects and implement practices that encourage them to stay.  Sometimes you have to sacrifice a bit of quality and a small pest problem to keep your beneficial alive and productive.

·         Exclusion – Some plants can be protected by keeping the pests off.  Essentially, you tolerate them in the neighbourhood, but you don’t let them live on your plants.  It is important to understand the habits and life cycles of the pests you might encounter.  Depending on the pest, you might protect using plant covers, short mesh screens (for those insects that are low flying), barriers around the base of the plants or other means of keeping insects from either feeding on or laying their eggs on or around the host plant.

• Lure and trap the scoundrels – If you can’t beat them in a direct and fair fight, trick them, then destroy them.  Many insects are drawn to plants by detecting the unique chemical “odours” put out by the plants.  Others are drawn by colour or other triggers.  Use this natural habit to your advantage.  Try the following:

o   Putt out trap plants – these plants serve as sacrificial lambs, which you either drop the bomb on or that you remove once they are loaded (or they just load up on the pests, while the plants you actually like pass unscathed.

o   Place sticky traps - these yellow or blue cards are meant for monitoring, but they catch a fair number of pests, as a side benefit.  They are simple, cheap and just need a bit of sticky stuff to be effective.  Their orientation relative to the ground and their height relative to the canopy will determine what you catch.  Change them when they start to fill up.

o   Place baits (liquid or solid) – these are geared to drawing the pests to where you can either remove them or kill them.  Some people use shallow pans of a beverage or maybe a partially buried piece of potato, depending on the pest.  You might need to change or “recharge” them occasionally, if they are popular.

• Remove and destroy – Some pests are big enough or occur in dense enough populations that you can pick them up and remove them (and perhaps the plant part that they are on) easily.  Anything that you can do to interrupt their life cycle and cut down the population, the better off you’ll be.  This method ties in nicely to trap plants or baits.  In lots of cases, you need to go after either eggs, adults, nymphs or other immature stages, such as larvae.  I still remember the Great Potato Beetle Hunt of ’85, where a bounty was offered for adults and larvae in a jar and for crushed egg groups. What I don't remember is being paid...

The overall message is that you can have healthy, good quality plants in your yard and garden.  You just have to take steps to accept, encourage, recognize and exclude and with some mental and physical exertion, you should make out fine.

Plants are just like People ... sort of.

Do you have a green thumb, or aspirations to such?  Do you ever get that sense that you relate better to something inanimate than to Billy Bob, your neighbour (this may depend a bit on who/what Billy Bob is, as well as the size of his truck)?  Or on the flip side, do you find the mysteries of the Plant Kingdoms beyond you?  Never fear.  Whether the world of photosynthetically-active green “people” calls or repels you, there is hope.  The two sides aren’t that different, at all.

Most of us humans have a reasonable understanding about what we need to live and thrive.  Plants are very much the same.  Meet the basic needs and you are good to go.  As a horticulturist, I am strongly inclined to explain things in terms of what plants do and how they act and react, sliding dangerously across the line that divides plant appreciation and the feeling that plants are live and interactive.

Regardless, please allow me to outline how plants and humans aren’t all that different.  For the plant-lovers, you’ll recognize the truth and maybe appreciate humans a bit more.  For those that don’t “get” plants, maybe you’ll gain a better appreciation and understanding about what makes those plants tick.  A few more plants will live and we’ll be the better for it.

Basic Needs:

In Mosby’s Medical Dictionary (8^th Edition – 2009), it defines the basic needs of humans as “the elements required for survival and normal mental and physical health, such as food, water, shelter, protection from environmental threats, and love.”  Without these things, humans can’t survive.  Indeed, in times of crisis, we work hard to restore a supply of the basics, before trying to get things entirely back to normal.

True to form, plants are really no different.  Plants need sunlight, air, water, nourishment, adequate temperatures and freedom from pests.  Let’s delve into each, since we want to learn more about how plants and humans are similar.

Light:

The fundamental function of plants is to capture and harness the energy the sun’s rays, converting it into products such as sugars, through processes that take in carbon dioxide (CO₂), water (H₂O) and other elements and releasing oxygen (O₂).  Without light, plants can’t capture the energy they need, create the food they (and others in the food chain) need and we start running a bit low on oxygen.

In the absence of light, or when light gets low, plants tend to be light-coloured or pale, even whitish.  Growth is weak, plants become stretched and spindly.  Over time, they diminish and eventually fall prey to illness or just die from starvation (essentially). 

Now, the non-plant people may be thinking, “We aren’t plants.  We don’t need sunlight to survive.  Why bother to even bring it up?”  You are partly correct.  However, I think that a good argument can be made that we do need sunlight to be healthy AND happy.  When we don’t get enough sunlight (and we need the sun to get Vitamin D – other than through supplements), we aren’t healthy.  Picture that weird cousin (you know the one) that never leaves the basement or house.  We become pale and anemic, pasty and weird (debatable).

The medical community now recognizes a disorder known as Seasonal Affective Disorder (SAD), which results in lack of energy, fatigue and depression, with typically “normal” activity in summertime.  SAD is also known as winter sickness, seasonal depression, winter blues, etc.  The basic treatment for SAD is simple: Sunlight.

People and plants that get too much sun have a similar reaction.  They experience tissue damage and don’t function properly for some time (remember how much it hurts to move with a lobster-esque sunburn).

Air:

We all need air to breathe.  Specifically, humans need oxygen.  Plants need air, specifically CO₂.  At higher levels of CO2, plants really thrive, because they become more efficient.  In conditions without any oxygen (anaerobic), both humans and plants don’t thrive.  They die.  Similarly, both plants and humans do poorly when air becomes stale and stagnant or polluted.  A bit of air movement and replacement of the air goes a long way to a healthy life for both of us.

Water:

Humans need water to stay alive.  We also use it to wash (ourselves and other things in our lives) and to stay cool and refreshed.  We are hydrated organisms.  So are plants.  Plants are comprised of up to 90+ per cent water.  Plants need water to maintain their cellular structure, for their physiological processes and reactions and to move elements things around within the plant.  Plants need a constant supply of water to stay hydrated and react very strongly to changes in both the soil moisture content and the relative humidity of the surrounding air.  Plants don’t sweat but they do make adjustments to ensure that there is fluid moving through them at the appropriate rate.  Plants can be protected from overheating and from freezing by the application of water.  Water is necessary to wash off the plant or plant parts, certainly after harvest.

If humans or plants are exposed to too much or too little water, they don’t do well.

Nourishment:

Whereas plants can produce their own “food products” from the sun, air and water and mineral elements in the soil, humans have to consume their nutrients (from plants or other animals).  Regardless, the need for food or nourishment is consistent between humans and plants.  When we think of food or nourishment for plants, we think more in terms of the supply of mineral elements (such as nitrogen, phosphorus, potassium).  Plants that are supplied with enough nutrients are healthy and productive, grow at a good pace and are more resistant to attack from disease or pests. 

Undernourished plants are weak, off-coloured and unproductive and may die.  Plants that get too much nutrition become unhealthy, in that they grow rapidly and weakly, often becoming soft and lush or tender and often sicken more quickly.  They can produce less fruit (and more leaves) and may “forget” to shut down for the winter.  Most of those descriptions sound a lot like what happens to over or under-fed humans.

Protection from the elements:

Humans need shelter.  This represents a protection from temperature extremes and other weather elements.  Plants need to be protected from these same things.  Plants (just like people) grow better at different temperatures, typically not the extreme ones.  If it gets below freezing (or even just colder), humans put on layers of clothing or go inside their homes.  Plants adjust somewhat, but then will eventually die.  The use of greenhouses, cold frames, or other plant covers (essentially “plant clothing”) are all that we can do to give plants a break from the colder elements.  Shading or misting is necessary to cool off plants when things heat up.

Space:

Humans need their personal space (some people forget this) and certainly do not thrive when they are packed like sardines into any particular space for an extended period of time.  Plants are no different.  Whereas the initial affect that many humans experience is probably more psychological than physical, plant overcrowding result in direct completion for limited resources.  Plants that have (too) close neighbours will be weakened or may be literally choked out (think of weeds).  The stagnant air that can develop will result in an increase in disease or other issues.

Plants that lack competition thrive to a certain extent, but also become a bit overgrown and wild.  Humans that lack contact with others become a bit wild or anti-social.

Freedom from pests:

No one likes to be sick, whether you are human or green.  We all suffer from various ailments and attack from different pests.  Humans take medicines.  We treat plants with “medicines” to try and fight off attack.  Both species become a little stronger if we are attacked in limited degrees.  But in general, we need to be free from pests or disease if we are going to thrive.

Love:

The original definition of basic human needs included a need for love.  It is interesting, but certainly not all that surprising.  We thrive on relationships, or are at least healthier contributors to society (remember your weird cousin?).  Are plants that different in this need for companionship or relationship?  They rely on us for a supply of nutrients, water and support (physical).  We protect them from the elements, from excessive competition and provide a bit of grooming.  Some might consider it a utilitarian and emotionless relationship, but anyone that has shed a tear after a frost or a big wind, knows that there is more to it.

Conclusion:

When you lay it out, it isn’t hard to see the similarities between humans and our green friends.  We both need some basic elements to survive and to really thrive.  The only thing that is maybe a bit different is that plants need to grow in soil (to supply structure/support and nutrients and water).  Humans don’t necessarily need dirt between our toes, do they?