- Author: Elizabeth E Grafton-Cardwell
- Author: Barbara Alonso
What happens once an odorprint shows the presence of HLB? Visit the Research Snapshot to learn more.
- Author: Ben Faber
Thanks for the rains that leach the soils of accumulated salts and bring on new fresh growth. Or maybe not. When we apply irrigation water with salts which with few exceptions we do in irrigated agriculture, salts accumulate in the soil. They accumulate in a certain pattern depending on the type of irrigation and soil type. There's a strong tendency for drip and microsprinklers to form a pattern of salt accumulation near the margins of the wetted patterns. This pattern is stronger with drip because the source point is always pushing a front outward from the emission point. This pattern occurs with microsprinklers, as well, although not as strongly. These patterns continue to form and accumulate as long as there is no rainfall to evenly push the salt down below the root zone. The longer the period of no rain, the larger the salt concentration at the margin.
So the way water moves is generally down. It moves in a wetting front drawn by gravity. It moves laterally too, because of the attraction water has for the soil particles. It will move laterally more in a clay soil than in a sandy soil because there are more particles in a clay soil than a sand (actually more surfaces that hold water). It also carries salt with it. Wherever the water moves, the salt moves. The more rain, the more salt is moved down. The more rain, the deeper the salt is pushed.
The problem with rain, is that if there is not enough, the salt tends to move laterally. In this wet soil solution, the salt is moving from where it is concentrated, to where there is a lower one. And if there isn't enough rain to move that salt down, it just moves back along the salt gradient, back to where the water first came from…….towards the roots. And that salt may be at such a high concentration that it can cause plant damage.
We talk about effective rainfall. This is usually about a quarter of an inch of rain. This is the amount of water to do more than just wet the dust, it's the amount to move water into the root zone. It is also moving salts into the root zone which can be a real problem. A good rain will do more than wet the dust, it will also move the salts out of harm's way in the root zone. The amount of rain necessary to do this is going to depend on the salt accumulated and the soil texture. The more salt, the more rain needed. The finer the texture, the more rain.
So there is no good cookbook, other than you need enough. And the first rains of the year, watch out. This is often when there is the highest salt accumulation and in the fall when we have the most irregular rains. Small rain amounts that can move salt into the root zone. A rule of thumb is a minimum of a good one inch rain event or combined rain events of two inches in a short period is needed to dissolve and move the salts out of the avocado root zone's top 18 inches. The more the better.
If there is not enough rain……………The solution !!!!!!!! Run the irrigation system to make sure there is enough to move that salt down.
Get ready to irrigate with the first rains if they are insufficient for adequate leaching.
Also get ready for the first smell of rain - petrichor.
Petrichor (/ˈpɛtrɪkɔːr/) is the earthy scent produced when rain falls on dry soil. The word is constructed from Greek petra (πέτρα), meaning "stone", and īchōr (ἰχώρ), the fluid that flows in the veins of the gods in Greek mythology.
The term was coined in 1964 by two Australian CSIRO researchers, Isabel Joy Bear and Richard G. Thomas, for an article in the journal Nature.[1][2] In the article, the authors describe how the smell derives from an oil exuded by certain plants during dry periods, whereupon it is absorbed by clay-based soils and rocks. During rain, the oil is released into the air along with another compound, geosmin, a metabolic by-product of certain actinobacteria, which is emitted by wet soil, producing the distinctive scent; ozone may also be present if there is lightning.[3] In a follow-up paper, Bear and Thomas (1965) showed that the oil retards seed germination and early plant growth.[4]
In 2015, scientists from the Massachusetts Institute of Technology (MIT) used high-speed cameras to record how the scent moves into the air.[5] The tests involved approximately 600 experiments on 28 different surfaces, including engineered materials and soil samples.[6] When a raindrop lands on a porous surface, air from the pores forms small bubbles, which float to the surface and release aerosols.[5] Such aerosols carry the scent, as well as bacteria and viruses from the soil.[5] Raindrops that move at a slower rate tend to produce more aerosols; this serves as an explanation for why the petrichor is more common after light rains.[5]
The human nose is extremely sensitive to geosmin and is able to detect it at concentrations as low as 5 parts per trillion.[7] Some scientists believe that humans appreciate the rain scent because ancestors may have relied on rainy weather for survival.
https://en.wikipedia.org/wiki/Petrichor
- Author: Jennifer Baumbach
Ask any gardener what their favorite plant is and I bet you will find they can’t name just one. Count me in that group. I love plants. But there are a few stand-outs that are worth mentioning.
For me, what captures my interest is either the color or smell of a plant. I love bright colors. Mostly oranges and blues. But I think that fragrance is the top attribute I look for in plants to add to my yard.
When I was attending Cal Poly, San Luis Obispo, I learned of this plant called Psoralea pinnata also known as the Scurfy Pea or the Kool-Aid® Bush. I had never encountered such a plant before. This was way back when I was just getting in to Horticulture, I was a late-bloomer with respect to learning or loving plants! (yes, pun intended) What caught my attention is the smell of the flowers. They smelled like grape Kool-Aid®! Seriously! The plant is somewhat ugly and rangy, but the blue and white flowers made up for that.
Since then, I have found a prettier substitute for the Scurfy Pea. This plant is in one of my favorite genuses, Salvia. The plant is Salvia melissodora known as the Grape-scented sage. It is a shrub that can get to 8 feet tall. It is native to the upper elevations of Mexico. The leaves also have an interesting smell, but not as good as the grapey fragrance of the violet/lavender flowers. To enjoy the smell, you have to avoid bruising the leaves, so don’t touch, just sniff. But be careful, as the carpenter bees and other bees visit this plant frequently. You don’t want a sting on your sniffer!
I have two of these salvias planted just outside my window. In the warm evenings of the summer, you can smell their delightful grape scent as it perfumes the neighborhood and of course, inside my home.
I recommend you open up your senses and try picking out plants with interesting fragrances to add to your own yards. You’d be amazed at what’s out there.
- Author: Betty Victor
Do plants see, smell, feel, hear, remember and know where they are?
These are some of the questions that Daniel Chamovitz who has a PhD in genetics writes about in his book “What a Plant Knows”. One of the discoveries scientists found in their research, was that plants and animals have some of the same genes as humans DNA.
Do they see? Plants do not have eyes like animals or humans, but according to some researchers they see when it’s light and when it’s dark, they seem to sense which side the light is coming from. Could that explain why they grow towards the light? What about plants that grow in the shade, do they wilt and die because of the light? My question is how does this explain night-blooming plants, where there is only a street light or the moon for light? How do they know it’s time to bloom or when night comes? Is this the sense scientists are talking about?
Do plants smell odor? We know that they are a lot of plants that have odor, roses, sweet peas, society garlic to name just a few, but some scientist studies show they can smell odors from plants near them as well as their own aroma. These scientists also think they can sense when their or their neighbor’s fruit is ripe.
Do they feel? Some say yes they suggest they can tell the difference between hot and cold, when something brushes them, the wind, animals or humans. Researchers also think plants are more sensitive to touch then we humans are. The slightest touch will cause some to close their leaves.
Can they hear? On this question there is little credible research that they hear, or if they do how they respond to sound. Yet we have all heard that talking to plants helps their growth. Is this a myth? Even biologists Charles Darwin, played his own bassoon to see if his mimosa plant (Mimosa pudica) would close- when it didn’t he called it a “fools experiment”.
Do they remember? Some of the plants memory faculties are the same as humans, but they don’t have memories like we do, they don’t remember sunshine or drought, but in their own way they do retain some past events such as any damage done to them by insects or humans.
Do they know where they are? Again scientists differs on this; some say yes, other are not sure. They say plants know roots grow down, shoot up, just like tendrils usually know where support is for them to attach to. So if a seed is planted how it does know roots grow down, shoot up if they are not aware where they are.
This is a very interesting book that I only touch the surface on, but for plant lovers it has a lot of information from the author and researchers on if plants see, smell, feel, hear, and remember.
