As Dan and I put the finishing touches on this newsletter it’s raining outside, with a forecast of rain all weekend. The outbreak of any disease can be described as the three sides of a triangle coming together. The presence of a host (peach); the presence of a pathogen (Coryneum blight) and the proper environmental condition (rain & temp). Fortunately the temps have been low enough to make an outbreak of fire blight or Coryneum blight or ? on the marginal side.
Reactive: Reacting to the past rather than anticipating the future
Proactive: Acting before a situation becomes a source of confrontation or crisis
Here’s an analogy to illustrate. When you cross the street do you stop at the curb and look both ways before stepping out (proactive), or do you just step out, then hope to jump fast and high enough to be safe (reactive)? As we start into this season take time to be proactive. Think back over the last couple of years about the factors that impacted your bottom line. Pest issues, disease, labor, the list can be long. It’s a good bet that the problems of last year will be back this season. Put a proactive plan in place!
Great news! The Cropworx “IT” department (John Kroll), has installed a search function on the newsletter archives page. What this means is that you can enter a word in the search box and instantly pull up any articles containing that word from the past 16 years of newsletters. Give it a try!
Should I add AMS (ammonium sulfate) to my spray tank when I use glyphosate? We get asked that question every year at the start of “weed season”. Yes is the answer and here’s why. Our water in Western Colorado is hard. That means that we have high amounts of Calcium and Magnesium dissolved in our water.
A water sample from the Grand Valley Canal showed 275 mg/L of CaCo3.
A level above 180 mg/L is defined as “very hard”.
Hard water ties up the glyphosate and does not allow it to be absorbed as easily into plants. The magnesium and calcium contained in hard water combines with glyphosate to form glyphosate-magnesium and glyphosate-calcium compounds which result in poor uptake and poor weed control.
Adding AMS to the tank FIRST does two things. 1) The sulfate ions tie up calcium and magnesium in the mix water which keep them from binding to (reducing the effectiveness) the glyphosate. 2) Some of the glyphosate binds with the ammonium to form a compound that improves the effectiveness of the glyphosate on some species of weeds, especially velvetleaf. The cost of adding 10# of AMS to a 100 gallons of water is minimal when compared to the improved effectiveness of your weed control.
“Cultivators of the earth are the most valuable citizens. they are the most vigorous, the most independant, the most virtuous, & they are tied to their country & wedded to it’s liberty & interests by the most lasting bands.” - Thomas Jefferson
Surfactants, also called wetting agents and spreaders, physically alter the surface tension of a spray droplet. For a pesticide or nutrient to perform its function properly, a spray droplet must be able to wet the foliage and spread out evenly over a leaf. Surfactants enlarge the area of product coverage, thereby increasing the plants exposure to the product applied. Think about how a drop of water forms a dome shape when sitting on your kitchen counter. Adding a surfactant to that drop causes it to spread out flat. Surfactants are particularly important when applying products to waxy or hairy leaves. Without proper wetting and spreading, spray droplets often run off or fail to adequately cover these surfaces.
Surfactants are classified by the way they ionize, or split apart into electrically charged atoms or molecules called ions. A surfactant with a negative charge is anionic, one with a positive charge is cationic, and one with no electrical charge is nonionic. Nonionic surfactants are compatible with most pesticides, and most EPA-registered pesticides that require a surfactant recommend a nonionic type. The only reason I would apply a tank of spray (conventional or organic) without adding an adjuvant in the mix is because the pesticide label recommends against it’s use, or the pesticide already contains one.
Spring is the most stressful time of the year for any fruit tree. Your orchard is drawing from reserves as it progresses through bloom. Soil temperatures are cold and limiting on nutrient availability. Fruit size is partially determined by the number of cells each fruit contains. Cell division occurs immediately after bloom (from 14 to 28 days after) when nutritional stress is at a peak. Healthy, well fed trees are better able to handle and size large crops, survive winter injury and pull buds through spring frosts. Next years’ flower buds are determined this season. Keeping a tree well fed is a year round program. Properly timed foliar applications of nutrients can help relief the stress!
The following is a seasonal use guide for nutrition. Remember, foliar feeding by definition implies the presence of active, growing leaves! The absorption of minerals through twigs and bark is minimal at best.
SEASON PHYSIOLOGICAL ACTIVITY CRITICAL ELEMENTS
Spring Bud-break & Initial growth N & P
Early Season Flowering, Foliage growth, N, P, Zn, B & Other Micros
Pollination, Fruit set
Mid Season Fruit & Foliage growth Ca, K, Mg & P
Late Season Sizing & Maturation Ca & P
Postharvest Nutrient Storage N, B & Zn
“The most humble research scientist in the Department of Agriculture is at this time contributing more to this country than the most useful member of Congress. “ — Fiorello La Guardia
I don’t know of a subject that draws more debate or varied opinions than that of calcium sprays. “It’s a must in my program!” “That calcium you sold me didn’t do a thing!” So what do the experts say? I read back through my collection of literature on calcium.
It functions in plant cell elongation and division, structure and permeability of cell membranes, nitrogen metabolism, and carbohydrate translocation. Considered a secondary or micro-nutrient even though the concentration of calcium in the plant is as great as nitrogen or potassium. Since calcium is part of the cell wall and acts as the cement that binds the cell walls together it is one of the most significant factors of firmness and storage life of fruit.
Water, containing elements and organic compounds, moves through the xylem up the tree. Stomates, which are small openings on the undersides of leaves, allow gases to move in and out of the leaf. Water evaporates from the stomatal openings in the process of transpiration, causing sap to be pulled through the xylem and into the leaf. This transpiration pull is responsible for the movement of water, containing nutrients, into the leaf and fruit.
Calcium moves very slowly in the tree and it may take more than a year for calcium to move from the roots to the leaves. Leaves transpire far more water than do fruit (stomates vs lenticels). Anything that reduces transpiration, such as high humidity, very low light levels, or drought stress, slows the movement of calcium up the tree. Because most transpiration occurs in the leaves, calcium moves preferentially into shoots and leaves, rather than into the fruit.
The cell division period is critical for Ca levels in the fruit. Early in the season prior to rapid shoot extension the fruitlet can accumulate Ca on an equal basis with other demands in the tree. Once the tree gets cranked up the Ca gets sucked right by the fruit. As fruit enlarges there’s no additional internal Ca supply! The concentration of Ca in the fruit declines for the remainder of the season.
There are several reasons that calcium deficiency symptoms show up in fruit:
· Quite often excess nitrogen is the cause. In an attempt to boost yields the first solution always seems to be ….. more N! A big shot of N causes the plant to grow faster than calcium can be moved within the plant. Nitrogen is translocated through the plant approximately 20 times faster than calcium. The increase in growth magnifies the problem.
· As a rule, the larger the fruit the less the Ca concentration.
· Excessive soil applications of K or Mg compete with Ca uptake, reducing it.
· Lack of adequate soil moisture, especially during the 1st half of the season when growing roots take up Ca.
So what’s the solution? Pay attention to your overall program. Don’t get too aggressive with vigor, don’t let the orchard suffer for water and keep your nutritional program within bounds. If you do decide to supplement with Ca, keep in mind the early window during bloom and immediately post bloom before rapid shoot extension starts. Later in the season, applications of Ca must contact the fruit to be effective. Give me a call to discuss the different formulations of calcium available.
Codling moth flight (biofix) generally begins in apples during bloom or shortly after, so traps should be in place by bloom. If mating disruption is used for codling moth management, dispensers should also be in place before bloom.
Those who did not add an insecticide for Peach Twig Borer with their dormant oil spray should consider an end of bloom/shuck split spray targeting this pest! The full bloom – shuck split timing is a great opportunity to deal with peach twig borer, thrips, aphids, mildew, coryneum blight and nutrition.
“Some of us grew up playing with tractors, the lucky ones still do”
As always, please give us a call with any questions!