Posts Tagged: A. I. Root
Planting Bare-Root Fruit Trees
There are several advantages to planting bare-root trees: they are usually less expensive, easier...
O'Henry Peach purchased bare-root and planted. Jeanette Alosi
What’s with all of the trash bugs this season?
I have received a handful of calls this season with concerns about “trash bugs,” a catch all term for various soil invertebrates. These soil invertebrates include root maggots, springtails, bulb mites, and symphylans, all which will happily feed on decomposing plant debris, i.e., trash. If given the opportunity, trash bugs will feed on seedlings and transplants, but high pressure can usually be avoided by allowing plant debris to fully breakdown before planting the next crop. A long enough pause between plant debris and seedlings acts as a sort of field-level host-free period, allowing trash bug populations to drop before planting.
Why does it feel like we have more trash bugs this season?
We had an unseasonably cool, wet spring. Under these conditions, crop debris from the fall was breaking down much slower than usual. With the compressed start to the season, folks have been eager to plant into fields as soon as possible, so many were likely planting into fields with higher-than-optimal plant debris.
By mid-April, daily temperatures were starting to get more back to normal, so why are we still dealing with more trash bugs? From talking with a handful of growers and PCAs, the slow start to the season has set back the whole planting schedule. To try and bring things back to schedule as close as possible, folks are still pushing the limit on how quickly they turn around fields for the next crop. A perfect storm for trash bug pressure.
Which trash bug am I dealing with?
A diverse group of pests can cause stunting and stand loss, so accurate pest ID is critical for successful management.
Root Maggots (seedcorn maggots or cabbage maggots, Delia spp.)
Root maggots are the larvae of small grey flies. The adult flies are commonly caught on sticky cards that are deployed for monitoring thrips and aphids.
Seedcorn maggot, Delia platura, seems to be the primary culprit that I have come across that is stunting brassicas. Seedcorn maggots tend to hit fields within a week or two after planting, causing patchy stands and stunted seedlings. Closely related cabbage maggots tend to hit fields a few weeks after planting and can continue to cause damage as plants mature.
To scout for root maggots, pull up stunted plants (see picture #1 below) and check roots for small, yellowish-white maggots (less than ¼ of an inch long). They can be easy to miss when they're all tangled up in the roots (picture #2). If scouting is delayed, you may also find the brown pupa (picture #3). With seedcorn maggots, timing a reactive control (i.e., insecticide application) can be tricky since the damage may go unnoticed until the maggots have already pupated and left the field.
From left to right: #1 broccoli stunting caused by root maggot feeding; #2 maggot tangled up in the roots of a broccoli plant; #3 root maggot pupa found next to a stunted broccoli plant. |
Springtails and soil mites
Pest springtails and soil mites are trickier to identify, since non-pest species are common in healthy soils. The one species of springtail that has been identified as an occasional pest of lettuce and brassicas is Protaphorura fimata, while the main pest mites are bulb mites (Rhizoglyphus spp., Tyrophagus spp.). Both P. fimata and bulb mites are small and whiteish while non-pest species are often larger and more colorful.
Clockwise from top left; Protaphorura fimata, the springtail species that can be a pest (Photo Credit: Shimat Joseph, previous UC IPM Advisor); non-pest springtails (note that these springtails are more colorful and have long antennae); a predatory soil mite (not a pest); and two bulb mites (Photo Credit: Jack Kelly Clark, UC IPM). |
Symphylans
Symphylans look like small (less than ½ an inch), white centipedes. Since symphylans are fast and mobile, you will be more likely to catch symphylans in action if you dig around stunted plants that are near healthy looking plants. If you readily find symphylans just by digging, the symphylan pressure is probably high enough to cause economic damage.
Lower symphylan densities can be harder to observe, so you may want to try bait-trapping with potato or beet wedges if you suspect symphylans but cannot find any by digging around stunted plants. The bait-trapping method can also be used to scout for springtails.
For more on the identification, scouting, and management of these pests, be sure to reference the UC IPM Pest Management Guidelines:
https://ipm.ucanr.edu/agriculture/cole-crops/
https://ipm.ucanr.edu/agriculture/lettuce/
Related blog posts from past entomology advisors:
Root maggots:
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=9804
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=4301
Symphylans:
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=18819
Springtails:
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=16769
Bulb Mites:
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=13271
/table>Perfect Timing for Publication of Important Research Paper on Root-Knot Nematodes
Perfect timing. Today, during the 62nd annual international conference of the Society...
An illustration from the PNAS paper: Rice infected by root-knot nematodes (stained in red). (Illustration by Shahid Siddique)
Newly Published Nematode Research: Hijacking Plant Development to Facilitate Parasitism
A UC Davis research team has discovered that “both a harmful plant bacterium and a...
An illustration from the PNAS paper: Rice infected by root-knot nematodes (stained in red). (Illustration by Shahid Siddique)
Selecting and Planting Bare Root Fruit Trees
Winter is an ideal time to plant a fruit tree. Although it requires some patience, success is best using bare root trees. There are many advantages: the trees are lighter and easier to handle; you can get a good look at the roots; they cost less than leafed-out potted trees; the tree is dormant and less apt to be stressed by handling; and the roots don't have to adapt again to new soil. The main disadvantage is that you should get the tree in the ground within a few days after purchase, and it may take 2–3 years before some trees produce fruit.
Fruit trees are an investment and deserve some thoughtfulness to ensure you plant the right tree (appropriate for your climate zone) in the right location (good drainage, minimum 6 hours sun per day). Digging the planting hole before buying the tree will let you check for drainage and an adequate amount (2–3 feet deep minimum) of soil. Here is a website showing how to test soil including drainage: https://marinmg.ucanr.edu/BASICS/SOIL_813/evaluate/
Selecting a healthy bare root tree is critical to get your investment off to a good start. Buy your tree from a reputable nursery that has a wide selection. You don't want a tree with roots that have been in a container too long. These roots may be kinked and will look like they are circling the root ball. These roots tend not to spread and that deprives your tree of needed nutrients.
When preparing the hole for your tree, follow the steps as described in the article linked below to give the roots room to spread and to prevent the graft site from sinking below soil level. Backfill with native soil. As you can see from the diagram below, most of the root ball should be above the original soil level to avoid crown rot. The tree will also settle.
And unless you want a huge tree with more fruit than most families could possibly eat, prune the trunk back to about knee height after planting. This takes some courage, but your tree will reward you with plenty of fruit that is easy to reach. Wait until the weather will be dry for at least several weeks to prune apricots, apriums, and cherries.
Other considerations are pollination requirements, ultimate tree size, chill hours, and disease susceptibility. Pollination is necessary for good fruit production. Some fruit trees have flowers with both male (anthers) and female (pistils) organs and can self-pollinate, such as persimmons and Bartlett pears. Other trees have flowers with both male and female organs but cannot self-pollinate and will require a second tree planted within 100 feet for fruit production, such as many apple varieties and Asian pears. Still others have separate male and female flowers.
Deciduous fruit and nut trees require a certain number of “chill hours” below 45°F to produce. It is important to select only varieties that have chill hour requirements equal to or lesser than the chill hours listed for your area. This reference discusses chill hours and has links to fruit tree requirements for Contra Costa County: https://ccmg.ucanr.edu/files/77176.pdf
It's important to know which diseases and pests a particular fruit tree is susceptible to. For example, apricots and their crosses such as aprium and pluot are prone to infection by the Eutypa fungus and unlike most deciduous trees, should be pruned in late summer before the weather gets damp. Check the reference below. These references have links and information regarding fertilization, pollination, pests and diseases, and characteristics of various fruit trees.
Despite our recent rains, we are still in a drought. Most fruit trees need substantial amounts of water to become established and as they mature and produce fruit. This link has information about drought tolerant fruit trees, shrubs and vines: https://crfg.org/wp-content/uploads/Drought-Tolerant-Fruiting-Trees-Shrubs-and-Vines-Presentation.pdf
Articles with step-by-step planting guides:
• https://sonomamg.ucanr.edu/Food_Gardening/Additional_KG_Articles/Planting_Bare-root_Fruit_Trees/
• https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=46072
• https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=38836
Excellent video with step-by-step planting guide (UC does not recommend any particular business but this nursery has good videos and does not advertise its products):
• https://www.youtube.com/watch?v=fP-2TGlNo50
More information:
• The Big Picture: https://homeorchard.ucanr.edu/
• Fruit trees for Contra Costa County – great reference to help you decide what to buy, and a pollinating guide: https://ucanr.edu/sites/ccmg/files/228958.pdf
• Fruit tree pests and diseases: http://ipm.ucanr.edu/PMG/GARDEN/fruit.html
Help Desk of the UC Master Gardener Program of Contra Costa County (EAS)