Growth and Care of Roots. Master Gardener Training January 12, 2011 Chuck Ingels UC Cooperative Extension, Sacramento County

Transcription

1 Growth and Care of Roots Master Gardener Training January 12, 2011 Chuck Ingels UC Cooperative Extension, Sacramento County

2 Larry Costello, UCCE SF & San Mateo Acknowledgments/ Selected Information Sources

3 Root Functions Absorption and transport of water and nutrients Storage of starch and nutrients Synthesis of hormones Anchorage

4 Emerging lateral root Anatomy of Young Roots Root hairs Cell elongation Root hairs Cell division Root cap Root cap

5 Root Cap Covers apical meristem Grouping of cells held within slimy mucigel Protects & lubricates root tip as it grows Cells slough off

6 Root Hairs Root hair Cells, not roots! Greatly increase root surface area Very short lived Nucleus Seed Primary root Root hairs Root apex

7 The Rhizosphere Region of soil that is directly influenced by root secretions (exudates) and soil microbes Exudates include amino acids, sugars, & acids Functions of exudates: Protect against pathogens Obtain nutrients Stabilize soil aggregates

8 Source: Roots Demystified

9 Mycorrhizae ( Fungus-Roots ) Fungal infection of roots symbiotic relationship Fungi receive sugars; plants nutrients & water Mainly P, but also NH 4+, NO 3-, and K + Poor growth without myc. where nutrients limited Lacking only in sedges & brassicas (cabbage fam.) Soil inoculation helpful only in poor/disturbed soils Two main types: Ecto- and endo-mycorrhizae

10 Mycorrhizal Fungi Ecto-Mycorrhizae Grow on trees in pine, oak, beech, birch, and willow families Grow outside and between cells of young roots

11 Mycorrhizal Fungi Endo-Mycorrhizae Most important is vesiculararbuscular myc. (VAM) 80% of plant species Most crops (monocots & dicots), hardwoods, non-pine conifers Infection directly into root cells

12 Mycorrhizae Poor growth of forest trees without mycorrhizae where nutrients limited

13 Depth of Rooting (Majority of Roots) Turf 8 to 12 in. Shrubs - Small 1 ft. - Large 2 ft. Trees - Small 2 ft. - Large 3 ft.

14 Turf Root Depths Most water & nutrients taken from 8-12 Source: Roots Demystified

15 Vegetable Root Systems Corn 1-ft. increments Plants grown individually in good soil Onion Tomato Source: Roots Demystified Pepper Caul. Carrot

16 Barley Fibrous Roots vs. Taproot Fava bean Clover

17 Tree Root Growth Mimics Top Growth NO!!

18 More Typical Tree Root Growth

19 Actual Root Growth of Mature Trees

20 Types of Roots in Trees 1. Tap 2. Oblique (Heart) 3. Lateral 4. Sinker 5. Fine

21 Types of Roots in Trees Sinker root Tap root Oblique root Lateral root Fine roots

22 1. Tap Root First root to emerge from the seed Rapid growth when young Other roots originate from it Strongly geotropic Year 1 Year 2 Many are <3 ft deep Coast live oak (Q. agrifolia)

23 Generally, tap roots do not persist. One study: Tap roots found in only 2% of 697 trees inspected Live oak Trunk Lateral roots Original tap root

24 2. Oblique (Heart) Roots Lateral Tap or oblique? Oblique root Develop from the tap root or shallow lateral roots Grow downward & outward Few fine roots Important role in anchorage

25 3. Lateral Roots Develop from tap root, form network of long, untapered roots similar to ropes Ash Branching, many fine roots at ends Water absorption and anchorage With trunk tissues, form trunk flare or root buttress Majority of root system of most species

26 Ash Lateral roots are dominant on some species but native oaks often have more oblique roots. Maple Ash Oak

27 4. Sinker Roots Lateral Roots Sinker roots Arise along lateral roots, typically within the drip line, near the trunk Grow vertically, vary in length Active in water and mineral absorption Provide anchorage

28 5. Fine Roots Small diameter (up to 2 mm) Often near soil surface Branch many times to form masses of thousands of roots Relatively short lived; some develop into lateral roots Most water and mineral absorption; large surface area with root hairs

29 Roots Find the Best Soil Compost holding area

30 Fine Roots Under Mulch

31 Lateral Root Development from Fine Roots

32 Lateral roots develop from cut roots as well; variability among species

33 Adventitious Roots Arise from trunks and branches Grape trunk hit by lawn sprinkler Air layering Rubber tree

34 Most roots are in surface 3 ft of soil. Uncommon for trees to root to depths greater than 6 ft.

35 Deeper Rooting in Dry Areas Roots have been found up to 75 ft. deep Engelmann oak (Q. engelmannii) San Diego Co. Blue oak (Q. douglasii) Sacramento Co.

36 Finding or Exposing Roots Pneumatic Excavation

37 Avoiding Roots and Pipes Pneumatic excavation would have prevented damage

38 Root System of Mature Gingko Tree Considered Deep Rooted Roots 12 below soil surface Soil line 4 ft.

39 From root excavations: From E. Gilman

40 Tree Protection Zone to Drip Line Is That Wide Enough?

41 Infrastructure Damage by Tree Roots

42 Tree-Based Strategies Matching Species with Planting Space the good

43 the bad

44 Fremont poplar.the really bad

45 the trend

46 Surface Roots in Lawns Liquidambar Sycamore (London plane)

47 Siting Your Tree Sacramento Tree Foundation Plant (large trees) at least 8 feet from sidewalks and driveways, 15 feet from home foundations and swimming pools, and 6 feet from fences.

48 Root Damage To Foundation Too? Chinese hackberry Root cut Drip line

49 Tree-Based Strategies Root Pruning Factors affecting impact: Size & number of roots, species, age, condition, proximity to trunk

50 Structural Failure from Pruning Roots

51 Reducing Infrastructure Damage Provide Adequate Space for Trees Magnolia in a 28 wide planting strip Callery pear in 5 x 5 cutout

52 better 9 x 12 ft. and even better 20 ft.

53 Curving sidewalks Pop-Outs Tree Islands

54 Reducing Infrastructure Damage Decomposed Granite Rutting when wet

55 Reducing Infrastructure Damage Grind Down the Concrete Liability issues with raised sections Grinding temporary will continue to lift

56 Reducing Infrastructure Damage Root Barriers

57 Reducing Infrastructure Damage Root Barrier Problems Roots also grow under barrier, then up

58 Barrier Too Low! Roots under concrete Linear barrier installed after root pruning Barrier

59 Root-Control Devices Tend to be most effective in soils where they are least needed: In well-drained, non-compacted soils Tend to be least effective where most needed: Where poor soil aeration or compaction encourages shallow rooting

60 Reducing Infrastructure Damage Structural Soil for Strength and Root Growth

61 Girdled Roots

62 Kinked and Twisted Roots

63 Straighten roots (preferable) or cut them

64 Pots to Direct Roots Downward

65 Causes and Effects of Unhealthy Roots

66 Tree Watering Basin Dead roots

67 Root-Knot Nematodes Problem in sandy soils Plants stunted Lettuce Tomato

68 Root Diseases Damping Off of Seedlings Fusarium Wilt of Tomato Root Rot of Gerbera

69 Rhizoctonia Root Rot

70 Crown Gall -FOHC Bacteria enter at wounds Can come from nursery Stunts/kills tree

71 Oak Root Fungus Armellaria mellea Rhizomorphs ( Shoestring fungus ) ORF Mushrooms

72 Phytophthora Crown & Root Rot Peach Avocado

73 Phytophthora Crown Rot Drip emitters (pink flags) were never moved away from trunk

74 1/4 long Garden Symphylans Garden symph. Centipede (top) Millipede (bottom) Arthropod, not insect Symphyla class White or whitish, 6-12 pairs of legs whiter and smaller than centipedes Diagnosis can be difficult Don t burrow through soil rely on good soil structure with pores

75 Garden Symphylans Significant crop losses Feed on decaying organic matter & roots, to 3 deep Problem on soil with good tilth, high OM, and low compaction Worse on heavier soils Root damage water & nutrient uptake, increased soil diseases Patchy populations hotspots

76 Garden Symphylans Sampling Sample when most active spring, early summer, fall Soil sampling Place soil from root zone on dark surface, count symphs Bait sampling Faster than soil sampling, but more variable results Works best 2-3 weeks after tillage Place half a potato or beet (red better) on soil surface, cover with white pot or large PVC cap 1-3 days later, count symphs on soil, then on bait

77 Garden Symphylans Management Rototilling Kills some, but only in surface Rototill when symphs are in surface soil (spring, early summer, fall) dry soil Crop rotation little known about which species most susceptible Avoid manure, use fine compost only 1-2 max. Use fallow; soil OM 3-5% max.

78 Use of Imidacloprid (Bayer) Perhaps the most sold pesticide in world Systemic translocation moves in xylem Kills sucking insects A few products: Admire (inject), Advantage (pets), Merit (landscape), Provado (spray)

79 Imidacloprid Soil Injection Methods Grid System: Injection sites spaced on 2.5 centers, in a grid pattern extending to drip line Circle System: Injection sites evenly spaced in circles extending to drip line Basal System: Injection sites around trunk (12 away max.)

80 Imidacloprid Basal Injection Sites = Injection Site (1 per inch of DBH) Research has shown this method works as well as grid

81 Imidacloprid Application Methods Soil drench Soil injection

82 Basal Injection Why it Works Soil application in late winter Taken up by fine roots only Many fine roots around and under the trunk Grid application misses many roots Research shows basal soil drench works just as well as grid drench Gaps within dripline Many roots below root crown