- Author: Richard Stouthamer
The recent find of the Kuroshio shot-hole borer in Santa Barbara shows that the beetle is expanding up the coast and it comes on top of the finding earlier this year of a single Kuroshio shot-hole borer in San Luis Obispo. Earlier yet in 2014 a single beetle identified as Euwallacea fornicatus was found by the CDFA monitoring in Santa Cruz county, unfortunately this specimen was only identified using morphological characters and therefore we do not know which of the three cryptic species of the Euwallacea fornicatus species complex we are dealing with for that particular find. After the single find (2016) in San Luis Obispo a several additional traps were placed in the vicinity of the first find but no additional beetles have been caught. In a single location in Irvine KSHB has also been detected last year (2015). Recently, the Kuroshio Shot-hole borer has also been reported in Tijuana Mexico, which is not surprising since the heavily infested Tijuana river valley park in San Diego county is less than 0.6 miles from the border with Tijuana. It is clear from these detections that the KSHB is on the move, just like the PSHB. These long distance moves by the beetles are most likely caused by human transport, and the most likely culprit is wood transported after trees have been cut down or trimmed. Both in San Luis Obispo and the location in Santa Cruz no additional finds have been reported, often the density of insects following an invasion of a new area remains low while the population is expanding and followed by it reaching such levels that they are “suddenly” detected in many locations.
- 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 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 the highest salt accumulation and the most irregular the rains. Small amounts that can move salt into the root zone.
If there is not enough rain……………The solution !!!!!!!! Run the water to make sure there is enough to move that salt down. Crazy, but a few months ago we had just this situation. It was one of the last rains in the winter and it was not enough to move salts down, and within a week many avocados showed leaf damage. It was sad since we had all been wanting rain, and we wanted a good drenching.
So why am I bringing this up now? Well, the other night I woke up to rain, glorious rain. I enjoyed listening to it and then it stopped. I thought O NO, it's not enough. There are going to be problems. Well luckily most places didn't get and where it did, it was a dust settler. But it made me aware that with the first rains we might see this fall, growers should be on their guard.
Get ready to irrigate with the first rains if they are insufficient for adequate leaching.
- Author: Ben Faber
Last Sunday was forecast as 20% chance of rain in Ventura, but it didn't happen. Today, Friday it was supposed to rain, but it's barely a drizzle. My car's dust has just been redistributed. Could a better prediction be forecast? According to Cliff Mass it certainly could.
http://cliffmass.blogspot.com/
http://www.nytimes.com/2016/10/23/magazine/why-isnt-the-us-better-at-predicting-extreme-weather.html
According to Mass, other countries like the UK and the European Union have invested heavily in computing power that allows greater prediction of local weather. In fact, the EU can forecast weather in the US better than National Weather Service. The problem at the Service is not for lack of imagination and smarts but a lack of funding for super computers that can do the improved predictions.
- Author: Ben Faber
Entomology Specialist and Lindcove Research and Education Center Director keeps her Asian Citrus Psyllid website for homeowners up-to-date at: http://ucanr.edu/sites/ACP/Homeowner_Options/Homeowner_Resources/
Check it out.
Photo: ACP Adult and Nymphs with wax tubules
- Author: Ben Faber
Calcareous soils have often more than 15% CaCO3 in the soil that may occur in various forms (powdery, nodules, crusts etc…). They are relatively widespread in the drier areas of the earth. California is notable for its young soils, that is, soils that have a relatively high level of nutrients because low rainfall means that natural productivity has not been leached out. The potential productivity of calcareous soils is high where adequate water and nutrients can be supplied. Water is the most limiting input to making California soils productive.
The high pH associated with these soils, though, is not the level of calcium present. It is the carbonate in the soil or the bicarbonate associated with the waters found in those soils which controls the pH. The high pH then controls the availability of iron, zinc, manganese and copper. These nutrients need to be added as foliars or soil applied, or better yet, the soil pH needs to be dropped to around 7 to make these nutrients available.
Recently someone asked if replacing the calcium with potassium would change the pH. No, it won't. The carbonate needs to be removed. Calling it a calcareous soil confuses people about what caused the high pH. The carbonate or bicarbonate needs to be removed with acidification, it turning it into CO2 gas. This is done with urea sulfuric acid or sulfuric or sulfurous acid. There are actually magnesium dominated soils in the San Luis Obispo area that have high pHs due to carbonates. They are carbonateceous.