- Author: Ben Faber
Avocado harvest time and the growers are in the orchard checking things out a little more closely and to see what is going into the bins…..and they see some unusual shaped fruit. Here's what's been popping up and some possible explanations.
Crick-side - First described by Dr. J. Eliot Coit as kink-neck and later by Horne (1931) as kink-side. Finally, the name crick-side (Horne, 1934) was adopted. It is characterized by a definite depression on one side between the stem end and the larger portion of the fruit causing a distortion. In some cases, the area of depression turns black and the fruit drops. In other cases, the fruit grows and matures but the distortion remains. Crick-side is usually found on trees carrying a heavy load of fruit. It has been suggested that high temperatures or temporary water-stress may relate to the occurrence of crick-side, but no definite determination as to its cause has been made.
Carapace Spot - First described by Horne (1929), the name carapace-spot was chosen because of the resemblance to a turtles' back. This external blemish is corky and usually cracked into somewhat regular, angular divisions. The flesh under the carapace spot is undamaged, but exterior appearance is such that the fruit is reduced in grade. Slight rubbing or brushing of tender young fruit on leaves or stems appears to cause this corky growth to start. Fruit on trees exposed to strong winds are more apt to develop the trouble. Windbreaks should reduce injury in windy areas.
Photo: Avocado thrips damage, carapace damage and greenhouse thrips damage.
Sunblotch - This is a viroid that can affect fruit, leaves, and stems with a yellow or reddish streaking, cause a compacted growth and willowy growth habit. The streaking in the fruit is usually depressed and doesn't extend the length of the body.
Sunburn - Fruit exposed to full sun may be injured by sunburn. This occurs when trees defoliate, or partially defoliate, from any of several causes, leaving the fruit exposed. It is normally most severe on fruit on the south and southwest portion of the tree. Sunburn shows as a pale yellowish area on the exposed side of the fruit. Often the center of this area turns brown to black and may wither.
Ring Neck - This trouble has been observed occasionally, particularly with Hass. The cause is unknown but is believed to be related to soil-plant water deficiency at a critical time. A ring of tissue on the pedicel just above the attachment to the fruit dies, turns black and peels off. If only superficial, the fruit remains on the tree. Growth may be retarded because the restriction impedes movement of nutrients and water outward to the fruit. Most severe in humid coastal areas.
Embossment - Occasionally, and particularly on Fuertes, a section of the surface will be raised slightly or be a darker or lighter color. This is referred to as a sectional chimera or genetic mutation.
Healed over damage - if fruit has mild damage that allows it to heal over (remember avocado fruit expand by cell multiplication not enlargement), then a scar is left, such as this likely amorbia feeding
Cuke - As in cucumber but not a squash. These are seedless fruit that can most often be seen from a fruit set in cooler weather or due to some hormonal stimulus. We don't know the reason, but seems to occur more commonly along the coast.
Double Fruit - In some instances there may be a normal shaped fruit with a single cuke attached ot in some cases there is a double ovary and two fruit are attached.
Woody Avocados - For some unknown reason, avocado fruit will form into a grotesque woody structure hardly resembling an avocado. The cause is genetic and non-transmissible.
Sources: R.G. Platt - California Avocado Society Yearbook 1972-73 and Reuben Hofshi and M.L. Arpaia Yearbook 2002.
- Author: Ben Faber
USDA Specialty Crops, the Agricultural Marketing News Service and What's Worth Planting
The AMS Specialty Crops Program helps buyers and sellers of all sizes in the U.S. produce industry to market their perishable products in the most efficient manner. They partner with State agencies and other industry organizations for the benefit of nationwide growers, shippers, brokers, receivers, processors, retailers and restaurants, direct to consumer sales, and the foodservice industry.
The program offers a wide array of services that span from helping market the quality of products to ensuring that there is fair trade in the produce industry. The program also helps specialty crops growers and handlers to combine their resources to help their respective industries overcome marketing barriers.
This is also a great website for trolling for potential alternative crops – what is selling, where, for how much and whether it might be a good idea to plant that crop. Check it out:
Main page of AMS:
https://www.ams.usda.gov/market-news/fruits-vegetables
Choose from different fruits:
https://www.marketnews.usda.gov/mnp/fv-nav-byCom?navClass=FRUITS&navType=byComm
For avocados you can see what the various prices are in different markets and times:
If you are interested in coffee prices, it's still considered a "commodity" and a California grown coffee will not be listed:
https://www.fas.usda.gov/data/search?f[0]=field_commodities:609
The USDA Specialty Crops Program also has a food safety certification program that might be of help to growers. In April 2016, the Specialty Crops Program's Specialty Crops Inspection Division (SCI) launched GroupGAP, a new food safety certification program that is part of our USDA Good Agricultural Practices (GAP) suite of services. Our voluntary USDA GAP programs help verify that produce growers and handlers have taken measures to reduce the risk of contamination. Commercial buyers look for USDA GAP-certified suppliers to source safe specialty products. While larger operations can devote the resources needed to become GAP certified, some smaller entities cannot. Until now. GroupGAP allows farmers, food hubs, and marketing organizations of all sizes to band together and pool resources to achieve USDA GAP certification.
- Author: Ben Faber
Diadasia bituberculata – Digger Bee
The hills are alive with the sound of BEE-EEZZE. And often they are found crawling on the ground, as is the case of Digger Bees. At this time of year, they might be seen along the margins of avocado orchards, near hiking trails or in undisturbed areas of citrus orchards. They are called Digger Bees commonly, but this is just a generic name for a large group of bees that nest in the ground. There are many genera and species and because of the general lack of study of these bees they are lumped under the name Digger for lack of any greater knowledge and naming of them. In the case of this bee find reported here, they are possibly Diadasia bituberculata – as suggested by Robin Thorpe, retired UCD entomologist. They are uncommon in the rest of the world, but found here in California and western US.
There are several kinds of small hairy or metallic bees that dig into the soil to nest, hence the common name, digger bees. They are a diverse group that comes from different families and the term digger bee can include the andrenid bees, halictid bees, and colletid bees such as the plasterer and yellow-faced bees. These are solitary bees and native pollinators that are active early in the season. Each female digs a cylindrical underground tunnel as a nest where she reproduces (as opposed to social bees such as honey bees where only the queen reproduces and maintains a colony with the help of sterile workers). Although solitary, they form colonies that may have several hundred nests in one spot, but all nests are independently owned.
The subterranean nest is provisioned with a mixture of nectar and pollen collected from nearby flowering plants. This "bee-bread" is food for the bee's offspring (larvae) that develop in the underground chamber and emerge as adults the following year.
Digger bees are 1/4 to 1/2-inch-long and variable in color (mostly shiny metallic or dark, but some with markings of white, yellow or reddish brown). There is one generation of digger bees per summer and once the adults finish perpetuating the species by laying eggs of the next generation there will be no activity till the following spring.
Digger bee nests are commonly located in areas where grass and mulch are scarse, either from too much shade, previous drought conditions or other stress. Most of them like to fly around their airspace at different times of the day, something to do with mating, air temperature or staking territory. They often travel great distances to forage.
The threat of being stung by digger bees is unlikely. The bees are docile and not likely to sting unless handled or threatened. There is no nest guarding behavior or attack behavior like there is with social insects such as honey bees and yellowjacket wasps.
Image: Digger Bee "Colony", Thanks to Pest Control Adviser Jane Delahoyde's friend.
- Author: Jim Downer
There's been a lot of avocado and citrus planting going on and this is a good time for a reminder about how to dig a hole. This is by our colleague Jim Downer in Ventura County, Horticulture Advisor and also past president of the International Society of Arboriculture, Western Chapter. In the text, where you see Fraxinus or some other tree name you don't recognize, just slip in avocado or citrus and keep reading. Also, check out the references.
Green side up! Oh, and do not sink the rootball below grade!
I have always been amazed at how the simplest of procedures or practices can go so wrong. For the green industry, the best example of this is planting. The act of putting green in the ground is our business. We do this. The problem is, we often do it wrong, carelessly, or without regard for the outcome—dead trees! A consultant friend often expressed how deep planting and covering the root ball with native fill are the most common mistakes he sees. I have to agree--landscape plants die at the hand of man more than from all the diseases and insects combined. There are various incorrect ways to plant a tree, such as adding too much organic matter to the backfill, installing a dry root ball and then not irrigating after planting, or adding too much fertilizer to the backfill. The practice I want to cover in this article is planting too deeply. The problem continues despite research about planting that recommends correct planting depths.
Planting depth is often ignored when plants are installed in landscapes.
Deep planting can result in death of woody and non-woody or herbaceous plants either because they rot (in moisture-saturated soils) or because they dry out. In either case, the symptoms are similar: wilting, sunscald or burnt leaves (necrotic tissues in the middle of the leaf), lack of growth, leaf drop, and eventually, necrosis of leaves, shoots and branches (all above ground parts). Irrigation usually does not improve symptoms because by the time they are noticed the plant has already been harmed beyond repair.
Root balls placed below grade cause several problems during establishment. Since native soil surrounds the root ball, there is an immediate problem with an interface between the two soil textures. Most container media are “light” to promote drainage characteristics necessary for container culture. When these soil-free media are planted in soil which is of a much finer texture, the resulting interface does not allow water to enter the root ball. Water must completely saturate the surrounding soil before it will cross the interface (Harris et al., 1999). As the plant draws down its container media moisture, the root ball desiccates beyond the permanent wilting point and the plant dies. This process is extreme in plants that are grown in peat-based media because the peat moss can become quite hydrophobic as it dries and then the interface issues are exacerbated. Special care should be taken with citrus and avocados to plant them at or above grade so the media itself is exposed to irrigations.
Acid plants are however, no exception to the above suggestion. Installing the plant at or above grade (if only ½-1 inch) will prevent excessive drying of the root ball due to interface smothering. It is however, very important that the root ball itself is irrigated in the first month of establishment not just the surrounding soil. Newly planted nursery stock does not absorb water from landscape soil, only from its own rootball. Until roots grow into the native soil, the plant must be irrigated to keep its rootball moist. The surface of the rootball can be protected with a coarse wood chip mulch.
Not all installers get planting depths wrong at the start. When the plants are first installed, everything looks good. The problem is sometimes related to the amount of digging used to make the planting hole. If the hole is dug too deep, and soil added back to bring the final grade to level, the plant can slump as water settles it. Digging destroys soil structure, so backfill under the rootball always settles - the plant sinks.Soil will wash in from the sides covering the root ball and sealing it from future irrigations.
Deeply planted woody plants are subject to diseases. The area where the roots of a plant join its main stem is the root collar. This area is very metabolically active and requires oxygen. In some cases, the stem above the root collar is green and photosynthesizes. Acer japonicum the Japanese maple has a clearly demarcated root collar region. Soil goes on the brown part and the green part should remain above ground. When the main stem is buried, the plant is predisposed to attack from canker forming fungi or other plant pathogens that can girdle the stem, killing it and all that grows above it.
It is quite clear from the literature that there is a strong species effect to the tolerance (or lack of tolerance) to deep planting. In a study of red maple and Yoshino cherry, only 50% of cherries survived deep planting, while there were no significant losses of maple to deep planting practices (Wells, et al., 2006). Arnold and others, 2007, found that green ash (Fraxinus pennsylvanica) was more tolerant to below-grade installation than golden rain tree (Koelreuteria bipinnata). In the same paper by Arnold et al., they showed that mulching can make deep planting worse. When trees planted below grade were mulched, mortality levels increased.
If plants survive deep planting, there can be other consequences. Wells and others 2006, showed that red maple (Acer rubrum) had increased numbers of girdling roots the deeper they were planted. When planted 6 inches below grade trees had 48% of their trunk encircled by girdling roots, when planted 12 inches below grade 71% of the trunk was affected.
Not all researchers found that soil over the root ball is detrimental. Gilman and Grabosky, 2004, found that if irrigation is plentiful (over an inch of applied water), trees survived and were less stressed three months later. Although planting depth did not impact growth of Southern live oaks, the study was relatively short term (7 months). I have also found in my own study of landscape shrubs that deep planting of five different genera of shrubs were not affected by planting depths of up to 4 inches below grade. The limitation of these studies is that they are short term. Over longer periods, disease and greater periods of hypoxia during high rainfall seasons may have cumulative detrimental effects not seen in the establishment phase of growth. When studied for three years, Arnold and others (2007), found that planting slightly above grade (3 in) improved growth of oleander and sycamore, while planting slightly below grade (3in) was harmful to all tested plants.
References
Broschatt, T. 1995. Planting depth affects survival, root growth, nutrient content of transplanted pygmy date palms. HortScience 30:1031-1032.
Arnold, M.A., G.V. McDonald, and D. Bryan. 2005. Planting depth and mulch thickness affect establishment of green ash (Fraxinus pennsylvanica and Bougainvillea goldenraintree (Koelreuteria bipinnata). J. Arboric. and Urban Forestry 31:163-170.
Arnold, M.A. G.V. McDonald, D.L. Bryan, G.C. Denny, W.T. Watson and L. Lombardini. 2007. Below-grade planting adversely affects survival and growth of tree species from five different families. J. Arboric. and Urban Forestry 33:64-69
Gillman, E. and J. Grabosky. 2004. Mulch and planting depth affect live oak (Quercus virginiana Mill.) establishment. J. Arboric. and Urban Forestry 30:311-317
Harris, R.W., J.R. Clark, and N.P. Matheny. 1999. Arboriculture: Integrated Management of Landscape Trees, Shrubs, and Vines. 3rd ed. Prentice Hall, Upper Saddle River, NJ.
MacDonald, J.D., L.R. Costello, J.M. Lichter, and D. Quickert. 2004. Fill soil effects on soil aeration and tree growth. J. Arboriculture 30:19-27.
Wells C., K. Townsend, J. Caldwell, D. Ham, E.T. Smiley and M. Sherwood. 2006. Effects of planting depth on landscape tree survival and girdling root formation. J. Arboriculture and Urban Forestry 32:305-311.
- Author: Ben Faber
A recent letter which followed a farm visit to another grower and finally a phone call about planting an avocado tree from another grower. The basics of planting are often overlooked and we should revisit them to make sure we know how to do the basics.
The letter:
I am going to plant some avocado trees on a slope. I will be drilling a hole with an 18 inch auger about three feet deep.
I have lots of wood chips from avocado trimmings. Should I mix some avocado wood chips with the soil to insure good drainage when I plant the new trees?
Or should I mix in some compost to help good drainage? Some areas here have poor drainage because of clay soil.
The response:
DO NOT put anything in the planting hole. It makes drainage worse. And if its not fresh the decomposing gases will kill the roots. And gradually over time, the organic matter decomposes and the tree sinks deeper into the ground, covering the graft union and the tree dies. I[m glad you asked. Someone is spreading the word that this is how to plant. It's a disaster if you do this. DON'T. You think you are doing everything right, but it is wrong. There's physics and biology involved and a good horticulturist knows better because of experience. Mulch applied to the soil surface is not the same as organic matter – planting mix put in the hole.
And watch out for the auger. Especially in heavy soils, the auger can seal the sides of the hole, making an impenetrable surface to the roots. The sides need to be scrapped or scratched to make sure the seal hasn't been created. And don't go 3 feet deep. Go to the depth of the planting sleeve. When you go deeper, the refill soil will compact and the root ball sinks, burying the crown.
From the UCR Avocado website:
http://ucavo.ucr.edu/general/answers.html#anchor1423493
Planting
The avocado is a shallow rooted tree (most of the feeder roots are in the top 6" of soil) which needs good aeration. They do well if mulched with a coarse yard mulch. Current recommendation is to put approx 1/3 cu yd per tree when planting. When applying the mulch, be sure to stay about 6-8 inches away from the trunk of the tree. They like the soil pH around 6 - 6.5. If you can, plant your tree in a spot protected from wind and frost. Also, avocado trees typically do not do well planted in lawns so try to plant your tree in a non-lawn area.
- When should I plant my avocado tree? Avocado trees like warm ground. Ideally, they should go into the ground from March through June. If they go in during the summer there is always the risk of sun damage because the trees can't take up water very well when young.
- How big a hole should I dig? As deep as the current root ball and just as wide as the width plus a little extra so you can get your hands into the hole to plant it. Don't drop the tree into the hole, the roots don't like that, ease it into the hole. The avocado root system is very sensitive and great care should be taken not to disturb the root system when transplanting. If the tree is root bound, however, loosen up the soil around the edges and clip the roots that are going in circles.
- Should I put some gravel, crushed rock or planting mix at the bottom of the hole? No. Do not put gravel or anything else like planting media in the hole. The sooner the roots get out into the bulk soil, the better the tree will do. Planting mix creates a textural difference between the root ball and the bulk soil and causes water movement problems. Remember, there are 5 million acres of tree crops in California planted without planting mix.
- I have a heavy clay soil. Should I elevate the tree in a mound for better drainage? Yes, good idea. Make the mound 1 to 2 feet high and 3 to 5 feet around. Put down 20 pounds of gypsum spread around the base of the tree and mulch the area with 6 inches of woody mulch keeping the material about 6-8 inches away from the tree trunk.
- What do you mean by a "coarse yard mulch" and where can I get some? Redwood bark will work and maybe cocoa bean husks and shredded tree bark. Need something that is woody and about 2 inches in diameter. Coarse yard mulch is available at some garden supply centers. Be sure it is COARSE, not fine, yard mulch - and disease-free to prevent introducing diseases to your tree (like root rot). Another source of coarse mulch would be a tree trimming operation, like Asplundh or Davy. They usually have material that has been pruned from the tops of trees and doesn't contain any diseased roots. Just go through the yellow pages looking for tree services.
These directions hold true of all trees, citrus, avocado, mango..............And for a nice discussion of avocado planting and root rot, go to:
http://www.avocadosource.com/journals/avoresearch/avoresearch_02_01_2002.pdf