Think Trees, and Drought!: Jim Downer University of California Cooperative Extension Ventura County

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1 Think Trees, and Drought!: Jim Downer University of California Cooperative Extension Ventura County

2 Trees Die

3 Drought Sespe Creek, Lyons, Camp 2014

4 Roots and Root systems

5 Oxygen deficiency Roots need oxygen to respire, without it they will die. Compaction, waterlogging, deep planting all reduce oxygen content around roots Street Tree in Kiev, Ukraine, 2015

6 Chestnuts in the Town of Pripyat a few Km from the Chernobyl Nuclear power plant within the 10Km exclusion zone. Site of the worlds worst nuclear disaster in man s history. Lenin Blvd, Pripyat, Ukraine 2015

7 Oxygen, Carbon Dioxide and Nitrogen oxide in soil The concentration of gasses changes with depth of soil. Roots often predominate in upper layers of soil because of this Add water and the graph changes dramatically Reduced temperatures also reduces oxygen concentration From: L.H. Stolzy, Zentmyer and Roulier. 1975

8 Root Anatomy There are many kinds of root systems Some root systems have no hair roots Ecto and Endomycorrhizae change the root appearance

9 Root Development

10 Mycorrhizae

PF 6:Mycorrhizal Partners (lack Conditions that favor mycorrhizal growth are also conditions that favor shade tree growth Litterfall, lack of compaction, moisture and

11 PF 6:Mycorrhizal Partners (lack Conditions that favor mycorrhizal growth are also conditions that favor shade tree growth Litterfall, lack of compaction, moisture and organic matter are all essential to mycorrhizal partnerships Many mycorrhizal fungi are also saprophytic fungi and rely on organic inputs to soil, i.e., Carbon! thereof)

15 Plant Physiology Plants are photosynthetic -- they gather their food energy directly from sunlight To perform photosynthesis, plants need to have a supply of: Sunlight Carbon dioxide gas from the atmosphere Water Mineral nutrients During photosynthesis, plants release Oxygen, but they need to use oxygen at night and in parts of the plant (like the roots) that do not perform photosynthesis. The structure of a plant is adapted to gathering the things that the plant needs.

16 Physiology Photosynthesis (6C H light C 6 H 12 O 6 +6O 2 +18H 2 0) 3CO 2 +6H 2 O + light C 3 H 6 O 3 + 3O 2 +3H 2 O Respiration C 6 H 12 O 6 + 6O 2 6C H 2 0 +Chem E + Heat Transpiration Water loss from plant surfaces due to Ps Guttation Water loss from plant surfaces due to Rs Hormonal regulation of plant growth Auxins, cytokinins, gibberelin, ethylene, abscisic acid

17 Cohesion tension theory of water movement

19 Roots have some unique structures Pericycle Endodermis Cortex

20 Solute movement Symplastic Apoplastic

21 Uptake

22 movement

Salinity, excess minerals in the root zone Salinity is a predisposing agent for root disease Excess salts in the root system cause roots to Leak metabolites that attract

23 Salinity, excess minerals in the root zone Salinity is a predisposing agent for root disease Excess salts in the root system cause roots to Leak metabolites that attract Zoospores High osmotic potentials prevent water movement into plants and require plants to expend energy to obtain water The Devil s Kitchen: Lassen Volcanic National Park

24 Salinity Is always a factor in the drought stressed western United States Is worst on unprotected (uncovered) soils Requires leaching with pure water to resolve Salinity = ET>PPT Leaching = ET<PPT

25 Drought increases Salinity and Salinity Uncovered soil exposed to direct sunlight will accumulate salts as water evaporates. Mulches can help reduce this* increases Drought! *Come back Friday for more on Mulch

27 Cavitation: Death of the xylem Vessel Elements

28 Cavitation leads to death of the When all the water columns in the wood break, the tree is at the permanent wilting point. The tree is dead! sapwood

29 Scorch Diseases More on Xylella diseases of ornamentals Xyllella fastidiosa is fast becoming a very important pathogen in many south western landscapes. Pathogen confirmed by ELISA and PCR testing Historic Olive Tree at Rancho Camulos in Ventura County

30 Bacterial Leaf Scorch Diseases Caused by strains of Xylella fastidiosa Almond Leaf Scortch White Oak

31 This is now a NM disease Look for it Found on Grapes, Peach, Chiptalpa (Las Cruces) and Catalpa in NM (N. Goldberg) Most Sharpshooters are not here in NM but here are native Xylem feeders including some sharpshooters.

32 Leaf Scorch Vectored by the glassy winged sharpshooter and other sharpshooters.

33 Leaf Scorch Symptoms Yellowing Necrosis Total death

35 What can we expect of drought Trees enter dormancy early Stress is increased Induced disease (Cankers) Insect attack is increased bark beetles Trees will die Physiological failures Disease Trees will not be replanted Deadwood and dying branches will be removed More sunlight will hit the ground increasing evaporation

36 USDA has revised their climate zone map to be 1-2 zones hotter now and in coming years Wall Street Journal, 12 January 2012

37 Expect more hot days per year Marcott et al., Science, ~ March 8, 2013 Holocene overall global temp from several types of records The reconstruction paints a picture of Earth gradually warming during the first half of the Holocene, and then, about 5,000 years ago, temperatures steadily dip to the coldest period of the Little Ice Age, about 200 years ago. Over these 5,000 years, the planet cooled 1.3 degrees Fahrenheit. Roach, NBC summary

38 Warming and Earlier Spring Increase Western US Forest Wildfire Activity Westerling et al Science Forest fires tied to climate change Increased length and duration of fire Tied to earlier spring and longer summer droughts in Western United States Forests

39 Pests and Diseases will increase Bark Beetles will continue to decimate conifers in North America Bark Beetles and other tree damaging pests will continue to expand their range Mountain Pine Beetle Due to warming trends pests not previously found in California will arrive and begin to damage trees and other plants

40 Insects that are increasing their range Emerald Ash Borer Asian Long-Horned Borer Asian Citrus Psyllid Walnut twig borer Golden Spotted Oak Borer Mountain Pine beetle

Figure 1 Geographic extent of mountain pine beetle outbreak in North America. a, Extent (dark red) of mountain pine beetle. b, The study area includes 98% of the current outbreak area.

41 Figure 1 Geographic extent of mountain pine beetle outbreak in North America. a, Extent (dark red) of mountain pine beetle. b, The study area includes 98% of the current outbreak area. c, A photograph taken in 2006 showing an example of recent mortality: pine trees turn red in the first year after beetle kill, and grey in subsequent years. Photo credit: Joan Westfall, Entopath Management Ltd. Kurz et al., 2008.

42 Symptoms of Drought Stress Hotter days mean more sunburn

43 Symptoms

44 Engraver beetles Can move spores of fungi that cause canker diseases Can vector blue stain fungi

45 Pine bark Beetles They have fungal affiliates that are necessary for the completion of their life cycles.

46 Ips, Dendroctonus Rapid death of Monterey pine is shortly followed by exodus of beetles from the dead trees.

47 Kurz et al., 2008, Mountain pine beetle and forest carbon feedback to climate change, Nature 452:

48 Allen et al Forest Ecology and Management

49 Ophiostomoa and Leptographium spp. Fungi are carried by pine bark boring insects and rely on their successful colonization of the tree before their own life cycles can be completed. Cause of blue stain in conifer wood.

50 Infections from the Ips beetles eventually invade most of the wood. Ophiostoma and Ceratocystis spread from the phloem to the sapwood and through the ray system. Fungi carried in the mycangium Blue Stain Fungi Mycangial fungi

51 Ceratocystis Fungi

52 Thousand Cankers Disease A new pest of black walnut that seems to be spreading in drought years. Geosmithia spp. Pityophthorous juglandis Walnut Twig Beetle

53 Thousand Cankers disease vector Pityophthorus juglandis

54 Thousand Cankers Disease Images by Whitney Crenshaw, Invasive.org.

55 TSD symptoms

56 Symptoms in stems A new canker disease in Ficus microcarpa nitida note branch collar is slowing progress of the infection.

57 Cankers usually caused by Botryosphaeria during drought Canker of unknown etiology on Corymbia citriodora Stegophora ulmea on Chinese Elm True Green

58 Canopy effects and symptoms Variable symptom development indicates a canker disease

59 Symptoms in Stems On thin barked or green-barked trees sometimes the stem must be washed to see the symptoms of a canker The effects of washing on symptom display on Ficus microcarpa nitida

60 Ficus Canker Anamorph Teleomorph

61 Drought Remedies Thin the landscape of excess trees Add hardscape Be cautious of turfgrass removal Protect valuable specimen trees From insects, disease and drought Delay replanting Apply mulch Judicious pruning

62 Adaptations Maintenance Survival Understanding the biology of trees and pathogens leads to an understanding of how to manage disease problems Poorly adapted trees will be adversely affected by drought and poor maintenance European Chestnut Kiev, Ukraine

63 Turfgrass eliminations Hard on Trees Turfgrass adapted trees will struggle unless new irrigation is installed to compensate for lost water

64 Pruning Thinning vs Overthinning Crown Cleaning? Removing green canopy from the tree can be detrimental. Green canopy removal is always growth preventing Opens canopy for sunburn during drought or summer months

65 Follow the Energy Energy comes from the sun to the tree and flows into many other organisms, many of them are fungi, a few of those are pathogens

66 Pruning Removing leaves removes energy producing cells

67 Pruning Removing stems removes stored energy Pruning is wounding Wounds are infection courts Pruning redirects the allocation of energy and tree hormones.

68 Wood is an energy storage and transport tissue

69 Stored Starch in Acacia melanoxylon From a healthy branch From a declining branch

70 Decay Depletes stored carbohydrates from living and dead wood Sapwood is a major storage organ for starch Decay fungi consume starch as they rot the wood Heart rot and sap rots not only remove wood but remove stored energy from trees

71 Heart Rot of Trees Ganoderma Laetiporus Often associated with a decline in vigor. Associated with wounds to roots or the main stem Wood decay fungi feed on stored sugars in wood and on the wood itself. Multiseriate rays stained with Potassium iodide to show starch storage in wood (Kevin Smith Seminar, San Marino, CA)

72 Natural Target Pruning 35 o 32 o ~35 o

73 44 o

74 25 o

75 Pruning Trees DO Don t Make the smallest wound possible Prune Frequently Structural pruning Pay attention to branch biology Conserve healthy canopy foliage Thin trees just to thin trees Remove over 25% of the foliage Cover wounds with pruning paints Make very large cuts Disrespect branch biology Make flush cuts

76 Irrigation Drip Netafim Micro spray Pressure Sprinkler Hits trees Broken systems Automated systems Misplaced water

77 Soil Sampling

78 Follow the runoff Water running off landscapes is often an indicator of over wet and poorly scheduled irrigations Trees often suffer greater root rot susceptibility in these landscapes. This happens continually during Drought

79 Netafim How? Why?

80 Irrigation practices exacerbate or predispose for root rot Irrigation practices Rates of application Placement of water Frequency of application Irrigation in relationship to edaphic factors Incompatible landscape features Ie Trees and Turfgrass

Trees are: woody complex, large, long-lived self-feeding shedding generating systems compartmented, self optimizing

BASIC TREE BIOLOGY Trees are: woody complex, large, long-lived self-feeding shedding generating systems compartmented, self optimizing Roots: absorb water and minerals store energy support and anchor