Sea lavender, Rust and Mildew

Abstract 7; Preface 9; Table of contents 11; List of abbreviations 17; 1. Natural pathosystems 19; 1.1. Homoeostasis 19; 1.2. Background information 19; 1.3. The present report 20; 2. The research area - Boschplaat - Terschelling - The Netherlands 21; 2.1. The "Boschplaat" 21; 2.2. The local climate 23; 2.3. The vegetation 24; 2.4. The research area 26; 2.5. Transect C 26; 3. The host, Limonium vulgare 31; 3.1. The sea lavender 31; 3.2. Genet growth 32; 3.3. Leaf development 34; 3.3.1. Leaf development indoors 34; 3.3.2. Leaf development in the field 36; 3.4. Roots 37; 3.5. Flowering and seed set 37; 3.6. Seed dispersal and plant establishment 39; 3.6.1. Generalities 39; 3.6.2. Plant establishment 40; 3.6.3. Spartina islands 41; 3.6.4. Seedling survival 43; 3.6.5. Vegetation development 45; 3.6.6. Morphological plasticity 49; 3.7. Age structure of sea lavender vegetations 50; 3.7.1. Genet age 50; 3.7.2. A logit line approach 51; 3.7.3. Age distributions of genets and vegetation types 51; 3.7.4. Age distributions within genets 53; 3.7.5. Decline of the sea lavender population 54; 3.8. Diseases, pests and other injurious agents 55; 3.9. Discussion 55. 4. The sea lavender rust, Uromyces limonii 59; 4.1. Uromyces limonii 59; 4.1.1. The species 59; 4.1.2. Pycnia 60; 4.1.3. Aecia 62; 4.1.4. Uredinia 64; 4.1.5. Telia 65; 4.1.6. Spore dispersal 66; 4.2. The effect of plant age 69; 4.3. Genet, isolate and interaction effects 70; 4.4. Half-sib progenies 72; 4.4.1. An unsuccessful experiment; a "growth chamber effect" 72; 4.4.2. A successful experiment 73; 4.4.3. A hybridisation experiment 73; 4.5. Salt and rust infection 75; 4.5.1. Salt and II-spore germination 75; 4.5.2. Effect of salt and rust on seedlings 78; 4.5.3. Plant vigour and rust infection 79; 4.5.4. Salt and host susceptibility 80; 4.6. Epidemics in the field 84; 4.6.1. Experiment 84; 4.6.2. Results per pustule type 85; 4.6.3. Results per leaf layer 88; 4.6.4. Summarised results of four genets 93; 4.6.5. The upsurges of the rust 93; 4.6.6. Summary of field experiments 96; 4.7. Discussion 96; 5. The sea lavender mildew, Erysiphe limonii 101; 5.1. The mildew 101; 5.2. Conidiospores 103; 5.2.1. Conidiospore germination 103; 5.2.2. Latent period 107; 5.2.3. Salt tolerance of mildew conidia 109; 5.2.4. Types of resistance 110; 5.3. Cleistothecia 112; 5.3.1. Development of cleistothecia 112; 5.3.2. Asci 113; 5.3.3. Ascospores 114; 5.3.4. Overwintering of cleistothecia and ascospores 115; 5.3.5. How to open cleistothecia? 118; 5.4. Indoor experiments 119; 5.4.1. The Leaf Fragment Method 119; 5.4.2. Leaf age and mildew susceptibility 121; 5.4.3. Between-ramet variation within-genets 121; 5.4.4. Variation in resistance of a seedling population 123. 5.5. Half-sib tests 126; 5.5.1. A leaf fragment test 126; 5.5.2. An intact plant test 127; 5.5.3. A hybridisation experiment 129; 5.6. Field epidemics 131; 5.7. Discussion 132; 6. Surveys 135; 6.1. The 1972 reconnaissance 135; 6.1.1. The 1972 Transect 135; 6.1.2. Detailed observations 137; 6.2. The 1973 reconnaissance 138; 6.2.1. General results 138; 6.2.2. Specific results 140; 6.2.3. The "contrast method" 141; 6.2.4. Combined occurrence of rust and mildew 141; 6.3. The 1979 Inventory 141; 6.3.1. Design of inventory and tests 141; 6.3.2. Vegetation types within disease classes 142; 6.3.3. Disease classes ranked per vegetation type 143; 6.3.4. The area-wide PL sample survey 145; 6.4. Transect C, 1978 + 1979 146; 6.4.1. Description of Transect C 146; 6.4.2. Results - aggregated data - distance effects 147; 6.4.3. Results - aggregated data - year effects 150; 6.4.4. Results - disaggregated data 156; 6.4.5. Autocorrelation and structure in Transect C 160; 6.4.6. The "mildew belt" 161; 6.4.7. Persistence of sea lavender pathogens at genet level 162; 6.5. Discussion 165; 7. Damage 167; 7.1. Damage, a key issue 167; 7.1.1. Injury, damage, loss 167; 7.1.2. Homoeostasis? 167; 7.1.3. The obvious 168; 7.1.4. The odd observations 169; 7.2. Mutilation experiments 170; 7.2.1. The 1978 experiment using octants within one genet 170; 7.2.2. Two 1979 mutilation experiments 172; 7.2.3. The 1980 experiment using 16 genets 172; 7.3. Field studies 175; 7.3.1. Impairment of genet growth by mildew, 1980 175; 7.3.2. Damage by low-level disease 176; 7.3.3. Impairment of foliar development by mildew, 1980 177; 7.3.4. Impairment of leaf and inflorescence formation by rust, 1978 179. 7.3.5. Impairment of flowering by rust, 1979 180; 7.4. Disease and succession 180; 7.5. Damage to seedlings 181; 7.6. Discussion 182; 8. Differential interaction in the sea lavender - rust pathosystem 185; 8.1. Differential interaction and physiologic specialisation 185; 8.2. Materials and methods 186; 8.3. Results 186; 8.4. Reciprocal checks 192; 8.5. Discussion 193; 9. General discussion 197; 9.1. Methodoly 197; 9.1.1. Technical aspects 197; 9.1.2. Statistics 199; 9.1.3. Reporting 199; 9.2. The multiple pathosystem 200; 9.2.1. Concepts 200; 9.2.2. The host 201; 9.2.3. The mildew 202; 9.2.4. The rust 202; 9.2.5. Perennation 203; 9.2.6. Speciation 204; 9.3. Disease and succession 204; 9.4. Robinson's proposal for an ESS 205; 9.5. Homoeostasis and ESS 206; 9.6. A metapathosystem 209; References 211; Appendix 1. Participants 217; Appendix 2. Inflorescence formation of 19 genets over three years, 1976-1978 218; Appendix 3. Scale to assess flowering stages of sea lavender 219; Appendix 4. Seed production in Transect C, 1978 220; Appendix 5. Data on age distributions within and between genets 222; Appendix 6. The agar disk method for inoculation with rust 224; Materials and methods 224; Results 226; Discussion 227. Appendix 7. Urediniospore germination experiments 228; Appendix 8. Effect of salt and rust on seedlings 230; Appendix 9. Table for mildew scoring 234; Appendix 10. The 1972 Transect 235; Appendix 11. The 1973 Survey. Leaves per ramet, healthy, rusted, mildewed or both rusted and mildewed 236; Appendix 12. Persistence of pathogens in Transect A 238; Appendix 13. Vegetation classes (VCs) in Transect C 240; Appendix 14. Mildew damage. Contrast method, PL around Transect C, 1980 242; Appendix 15. 1979 data on rusted and (nearly) healthy genets in PL 244; Appendix 16. Consultant's Report on EPINAT, 1979 245; Contents 245; 1. The Consultancy 245; 2. The Global Context 245; 3. The Pathosystem Concept 246; 4. The Artifacts of Agriculture 247; 5. The Concept of the ESS 247; 6. Evolution of the Vertical subsystem 248; 7. The ESS of the Vertical Subsystem 248; 8. Model of the Limonium Mildew Pathosystem 250; 9. The concept of syergetics 251; 10. Suggestions for future research 252; 11. Recommendations 253.