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Water Woes

Water Woes

If you live in a place where water falls from the sky during summer this blog is perhaps not so helpful. However, gardeners in much of the western United States will suffer this summer from hot days (sometimes record breaking) and will need to irrigate their gardens and trees in order for them to survive impending drought conditions. The ongoing drought has drained reservoirs and flows of rivers are down or, in some cases, dry entirely. Due to water scarcity, purveyors are restricting water use outside of homes and in some cases curtailing all landscape irrigation. Using water wisely in the landscape has never been more relevant than now. In this blog post we’ll continue to explore saving our gardens from drought and touch on water use, water demand and plant stress.

Good news — Bad news

The good news is that the longest day of the year was last month. That means that the days are ever so gradually getting shorter. As days shorten, plants use less water. Water use is tied directly to photosynthesis and when the lights are out there is no photosynthesis. Shorter days mean less demand for water. The bad news is that we may have record breaking hot days ahead. Plants become susceptible to wilt, sunburn and dieback during very hot weather. The best way to prevent this is to ensure that roots are moist during very hot weather.

The combination of drought and heat caused sunburn to these privet leaves

Mediterranean Climate

It turns out that in Ventura, CA the longest day of the year is one of the historically driest months (least rainfall) and the shortest day occurs in a month with more rain than average…

…click on the above link to read the rest of the article…

*Summertime, and the livin’ is easy…

*Summertime, and the livin’ is easy…

If you listen closely you can hear the beasties in your garden just a-singin’ that tune. And who can blame them? Warm temperatures and lush green gardens? They enjoy them as much as we do. But sometimes they can be enjoying our landscape a little too much. So now what do you do?

Visit the garden chemicals section at your local big box store? Reach for your favorite “natural” or DIY concoction? Ask your neighbor?

Hmmm, maybe not.

What is the best way to deal with the problem? Three letters answer that question. IPM.

Scoutcat logo courtesy of C. Ware, copyright 2000

What is IPM? Integrated Pest Management (IPM) is the management approach you should use to solve pest problems. It can manage all sorts of pests with minimal risks to people, pets, and the environment. IPM’s emphasis is on the management of problems rather than eradication. It focuses on long-term prevention of pests or their damage by managing the ecosystem.

IPM is a five step process: 1) correct pest ID, 2) monitoring and assessing pest numbers and damage, 3) pest ID guidelines for when management action is needed, 4) preventing pest problems, and 5) determining correct control measures. Let’s take a look at each one.

#1. Pest ID

Correct ID of the problem-causing critter is the most important aspect of IPM. If you don’t know what you’re dealing with, how can you devise an effective control strategy, if indeed one is needed?

So what is a pest? Pests are organisms which damage or interfere with desirable plants or damage structures. Pests also include organisms that can impact human or animal health. Pests may transmit disease or may be just a nuisance. A pest can be a plant (weed), vertebrate (bird, rodent, or other mammal), invertebrate (insect, tick, mite, or snail), nematode, or a pathogen (bacteria, virus, or fungus).

…click on the above link to read the rest of the article…

February is…

February is…

…National Pesticide Safety Month. Let’s review some key points of safe pesticide use.

Socrates said, “ The beginning of wisdom is the definition of terms”

So let’s define a pesticide.
A simple definition is any substance used to control, deter, incapacitate, kill, or otherwise discourage organisms harmful to plants, animals or humans can be classified as a pesticide. A fuller definition can be found here. Germane to our discussion, herbicides make up 80% of all pesticide use. As gardeners we should know how to properly handle any chemicals we choose to use.

Anytime you use a pesticide, be sure to read and follow label instructions. The label will include important information for protecting yourself and it will tell you how to apply the product in the way that it will work best. Be certain the pesticide you’re using is correct for the job.

 

All pesticides carry labels which provide varying levels of information including the signal words “Danger”, “Warning’ or “Caution”. These signal words have specific meanings in relation to the pesticide. Products labeled “Caution” are the least toxic, “Danger” are the most. More information on signal words can be found here.

Correct and controlled application is responsible pesticide use. While some pesticides can be broadcast, e.g., pre-emergents and some lawn grub control products, most of them need to be precisely applied. Use correctly calibrated equipment recommended by the label directions and apply precisely. Avoid overspraying and watch out for drift.

And finally, wear protective clothing and use the correct application method and equipment as stated on the label. Always keep children and pets away while you’re applying any product. Observe wait times before allowing people or pets back into or onto treated areas. When you’ve finished application wash your hands, face and any skin that’s been exposed to the product. If needed, launder protective clothing separately from other clothing.

For more information:
https://www.epa.gov/safepestcontrol
http://npic.orst.edu

Pruning newly planted trees

Pruning newly planted trees

As the climate warms the value of trees for cooling the environment around buildings, especially in cities, drives tree planting programs. Planting trees is just the first step in growing a tree in a sustainable landscape. Successful plantings require evaluation and guidance of the new tree’s current and future branch architecture. In almost every case, nursery grown trees will require some structural pruning so that a shade tree can develop strong and effective branch attachments that will support the canopy for the coming decades without failure. In this blog I cover maintenance of the newly planted tree including how to structurally prune young trees so that they develop strong and sustainable canopies.

As mentioned in earlier pruning blogs, trees do not require pruning. This is predicated on the assumption that trees are allowed to grow in the way they are genetically programmed to grow without damage. Unfortunately many container nurseries prune trees with a heading cut to the central leader in order to create branches that can further be pruned to make a “lollipop” canopy that mimics the form of a large tree. Consumers have become accustomed to this “in-pot” miniature version of a shade tree and nurseries are accustomed to producing them. Low branches are removed to enhance the tree lollipop shape. Nurseries often stake trees tightly to provide a way to keep them from being blown over in wind events and since all the temporary branches are removed from the low trunk they are top heavy and require rigid staking usually with a stake taped to the trunk. Tightly staked trees grow taller than unstaked trees and their trunks may lack caliper or taper (increase in trunk diameter lower on the stem)…

…click on the above link to read the rest of the article…

Diagnosing Abiotic Disorders II

Diagnosing Abiotic Disorders II

In this blog I continue to examine maladies caused by environmental conditions in the absence of a disease agent or insect.

Salt affected plants show damage to older leaves starting from the edge of the leaf and moving inward.

Salinity
Salt in soils or water is simply the presence of too many soluble ions in the soil-water solution. This tends to happen in dry climates where evaporation rates exceed precipitation rates. In these climates salts accumulate in soil when surface waters pick up minerals from soil that is high in precipitated salts. In wetter climates water leaches salts from soil so surface waters (rivers and lakes) have fewer dissolved salts. Also, in dry climates irrigation is often a must and irrigation sources usually have high amounts of dissolved salts. In high salt environments plants must use energy to increase their own salt balance at the root interface to make uptake of fresh water through their membranes possible. This energy is thus not available for growth. Salt affected plants are often smaller, even stunted depending on salinity levels and are more susceptible to root pathogens as their roots are more likely to be “leaky” giving pathogens chemical signals of their susceptibility.  Salt damaged leaves often show “edge” necrosis or burning on the oldest leaves.

Salt affected soils should not be allowed to dry out as roots will be damaged. Leaching to dissolve salts and move them below the root zone is one approach to prevent further symptoms.

In this soil salts have precipitated on the soil surface because evaporation exceeds precipitation

Soil compaction
Soil compaction is the increase in soil bulk density beyond a point where roots function and grow. Bulk density is a measure of soil compactness and is calculated as the weight of dry soil per volume…

…click on the above link to read the rest of the article…

Water: Garden Friend….and Foe? – Water, Relative Humidity, and Plant Diseases

Watering can and vegetable garden

Water: Garden Friend….and Foe? – Water, Relative Humidity, and Plant Diseases

We all know that water is essential for life and that we have to ensure our landscapes, gardens, and houseplants all have a sufficient supply of the stuff.  Forget to water your garden during a hot, dry spell and it could mean disaster for your plants.  But water can also create issues for plants, usually when it is in an overabundance – water helps spread and develop diseases on foliage and excess soil moisture can damage roots, creating opportunities for root rots and other diseases.  How do you meet the water needs of the plant while also avoiding issues associated water?  Understanding how water affects disease organisms will help, along with some tried and true Integrated Pest Management Strategies.

Water and Pathogenic Microbes

Both bacteria and fungi require water to grow and reproduce.  Most do not have a mechanism to actively take up and manage water, so they uptake water mainly through osmosis.  This means there must be some form of water present for those microbes that are actively growing and especially for processes like reproduction which use not only a lot of energy but might also be required to carry spores in order to spread.

File:Septoria lycopersici malagutii leaf spot on tomato leaf.jpg -  Wikimedia Commons
Septoria leaf spot, a common fungal disease of tomato that requires water for initiation and development.

Both pathogenic microbes and beneficial (or neutral) microbes require water to thrive.  It is one side of what we refer to as the disease triangle.  Water (along with temperature) are major components of the “favorable environment” side of the triangle, with the other sides being a plant capable of being infected and a population of pathogens capable of infecting.  Those last two sides meaning you have to have a population of the pathogen big enough to initiate or sustain an infection and a plant that can actually be infected by that pathogen.

…click on the above link to read the rest of the article…

“PoP” Goes the Weasel

“PoP” Goes the Weasel

How do you plan your work in your garden? One of the things that is most likely to affect what you do is rainfall. But how do you know when and how much rain is likely to fall? One way to get an idea of the possibility of rain is to look at something called “Probability of Precipitation”, or as we call it, “PoP”. How often have you heard someone say that the weatherman (or woman) was wrong because they predicted 30 percent chance of rain and they did not get anything? Or someone else says there was only a 10 percent chance of rain and they got flooded? If you understand how these forecasts are made, it might help you plan your outdoor activities, including your garden work and when you water.

Source: John Robert McPherson, Creative Commons

How is “PoP” defined?

According to the National Weather Service (NWS):

PoP = C x A where “C” = the confidence that precipitation will occur somewhere in the forecast area, and where “A” = the percent of the area that will receive measurable precipitation, if it occurs at all. The forecast is what we call a “conditional” forecast—that means it depends on two different things, one of which requires the other to occur. It’s important to keep in mind that these forecasts are made for a particular period of time (often 12 hours) and for a particular area (the forecast zone). The first part of the calculation is whether or not it will rain at all anywhere in the forecast zone during the time that the forecast covers. The second is how much of the forecast zone will be hit by precipitation sometime during the forecast period.

How likely is it that precipitation will occur?

…click on the above link to read the rest of the article…

Contain Yourself: Vegetable gardening in containers and small spaces

Contain Yourself: Vegetable gardening in containers and small spaces

Given the growing (haha) popularity of vegetable gardening over the last several years, which has gone into overdrive during the pandemic, more and more people are looking for innovative ways to grow in all kinds of spaces. Container vegetable gardening can be as simple as popping a tomato into a bucket, but there are lots of different ways to successfully grow crops in small, mobile containers. It is possible to grow full sized crops in containers, given a large enough container and space to grow. But more and more plant breeders have been developing small and dwarf cultivars of lots of different kinds of crop plants to meet the burgeoning interest in container and small space gardening. Let’s talk a bit about growing in containers, about some of those crops that do well in containers (including some dwarf/small cultivars, and even some design to make those vegetable containers attractive on your patio or porch.

Container Culture

Growing vegetables and fruits in containers follows the same general rules that ornamentals and houseplants follow. We’ve covered several container questions here on the GP blog, which you can find here. Probably one of the biggest questions (and myths) that we encounter is the placement of rocks or other items in the bottom of pots for drainage. It is a common question over on our social media. So to just get that out of the way, don’t do it – it actually makes drainage worse. The only exception might be if you are using a really large, deep pot and need to fill it with something so you don’t have to fill it all the way with soil – but you still need to ensure that the soil is sufficiently deep so that you don’t end up with waterlogged soil in the root zone.

…click on the above link to read the rest of the article…

“Water, water, everywhere…

“Water, water, everywhere…

Did it rain enough last night to water your garden? Have you started running the sprinklers and aren’t sure if they’re running enough? Perhaps you’re not sure that new drip system you installed is doing its job. Or maybe you just want to be more efficient and careful with your water use. How can you know moisture is getting deep enough into the soil to benefit your plants. Is there an easy way to find out?

Yes there is – a simple soil probe will do the trick.

A soil probe can be anything long and sturdy enough to penetrate the soil at least 12 inches (~30 cm.). Handmade soil probes, long screwdrivers, skewers, even the spit from an old rotisserie grill will all work.

A probe made of metal will work best and for safety it should have a handle of some sort. If there’s no handle you should wear sturdy gloves when using it. This set of  22″ screwdrivers was purchased at the local outlet of a national low cost tool franchise. It meets all the requirements and is inexpensive. Plus it’s a set so there’s one for you and one to share!

While you only need the probe to go 12″ into the soil it’s helpful if the probe itself is longer, if only for convenince. The probes are shown here with a yardstick for scale. (Yardstick = 36″=~91.5 cm.)

So you now have a soil probe, how do you use it to measure soil moisture depth? Easy-peasy.

Insert the probe straight into the soil at the spot you want to test. You’ll need to use firm pressure but don’t force it into the soil. The soil will pass through moist soil but stop when it hits dry…

…click on the above link to read the rest of the article…

My Soil Is Crap, Part II

My Soil Is Crap, Part II

Last month in my blog My Soil Is Crap Part I, I tried to dispel the myth that you can diagnose soil problems by just looking at your soil. While the color of a soil does impart some diagnostic qualities, most soils are not easily analyzed without a soils test. A complete soils test will give a textural analysis including useful information about water holding capacity and a variety of chemical analyses. Soil reaction or pH is an essential component of any soil test (and is often unreliable in home soil test kits). Soil reaction affects the availability of plant required mineral salts. Most soil tests give a measure of the salinity sometimes call TDS, or total dissolved salts (solids). Finally specific mineral content of soil is usually analyzed – in particular macronutrients are usually quantified. With these data a great deal can be predicted about the “grow-ability” of your soil. Soil tests can also help guide attempts to modify soils. The biology of soils is not easily or routinely analyzed through soils tests.

Soil Harm

Soil can be “harmed” in several ways–making it less able to grow plants. Or another way to look at this is that soil can be enhanced in several ways to grow plants better. First let’s examine the harm. Soil can be physically harmed by tilling with a rototiller. Tillage destroys structure and the natural clods and peds that form over time because of a soil’s innate qualities. Structured soils support plants and help prevent disease. Tilled soils will in time resume their native structure, but the amount of time required is quite variable depending on soil type. Soil structure can also be squished– this is compaction…

…click on the above link to read the rest of the article…

Olduvai IV: Courage
In progress...

Olduvai II: Exodus
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