From planning to planting: The latest information for establishing new groves in the presence of HLB

Transcription

1 From planning to planting: The latest information for establishing new groves in the presence of HLB Ute Albrecht Southwest Florida Research and Education Center UF/IFAS, Immokalee, FL

2 Important factors to consider Tree selection Site preparation Planting Irrigation Nutrition Weed management Pest control

3 Tree selection

4 . Tree selection Purchase only high quality nursery trees from reputable registered nurseries. Inspect trees before planting. Select only well-formed trees. Do not use trees with irregular root system. Trees should not be pot-bound.

5 Scion selection Scion selection will depend on preference and the predicted economic potential. All commercial varieties are susceptible to HLB. Some varieties appear to perform better under HLB pressure (Sugar Belle, UF ).

6 Scion selection Within grapefruit, Triumph and Jackson are less adversely affected by HLB than Flame and Marsh. (Stover et al., 2012) Minneola, Fallglo, and Bower are less susceptible than other varieties such as grapefruit, Temple, Valencia, Hirado, Orlando, Sunburst, Dancy, and Ambersweet. (McCollum et al., 2016)

7 Scion selection Many new UF/IFAS scion selections have been released for the FAST TRACK program and are currently under evaluation. (Grosser and Gmitter)

8 Rootstock selection Select based on soil characteristics, pest and disease pressure, desired spacing and size control, and other desired traits. Trees on some rootstocks perform considerably better under severe HLB pressure.

9 Rootstock selection Valencia field trial (2008) - Polk County Bowman, McCollum, Albrecht (2016)

10 Rootstock selection Many promising UF/IFAS rootstocks have been released for the FAST TRACK program and are currently under evaluation. (Grosser and Gmitter) Choosing the right rootstock will result in higher economic returns without any additional cost.

11 Rootstock selection (Castle, Bowman, Grosser, Futch, Graham)

12 Site preparation

13 Site preparation Prepare site several weeks before planting to allow remaining plant material in the soil to decompose. Aerate soil and remove weeds and any remaining citrus roots prior to planting. Use non-residual herbicide (preferably). Plant at least 2 feet away from any remaining tree stumps

14 Drainage Site preparation Likely sufficient in the sandy soils of the central Florida ridge area. Soils are usually wet in the flatwood soils of the southwest and eastern areas of Florida and must be well-drained.

15 Drainage Site preparation Drainage systems should consist of water furrows, ditches or tile drains and a perimeter ditch to remove excess water. Trees are usually planted in double rows on raised beds with crowns at least 3 feet above the bottom of the furrow.

16 Planting

17 Planting Base tree spacing on the expected size of your scion/rootstock combination and the expected life of the grove. A more densely planted grove may provide an earlier economic return despite an initial higher investment. Refer to the rootstock selection guide for information on spacing.

18 Planting Ideally, trees should be planted the same day they are received. Loosen potting soil to expose roots to the surrounding soil. Pot-bound roots need to be pruned/ slashed to encourage new growth. Set soil line of trees about 1 inch higher than surrounding soil. Never allow your trees to dry out!

19 Trunk protection

20 Trunk protection Wraps should be placed around young trees in the first years. Wraps inhibit sprout formation. Wraps provide protection from herbicide applications and mechanical damage. Wraps provide freeze protection. BUT: Inspect wraps for insects (especially fire ants).

21 Irrigation

22 Irrigation Irrigation requirements depend on many factors, including rainfall, temperature, time of year, and soil characteristics. Irrigation scheduling has a direct impact on tree health, fruit quality and yield. Without correct scheduling, trees are more susceptible to nutrient deficiencies, physiological disorders, pests and disease.

23 Irrigation The primary objective during the first years is the rapid development of the tree canopy to ensure fruit production in the coming years. Vegetative growth is very susceptible to water stress. Therefore it is very important to maintain adequate soil moisture at all times.

24 Irrigation Microirrigation systems

25 Irrigation Advantages of microirrigation: Cost-effective. Reduced water use. Fertilizers and other chemicals can be applied with irrigation. Precise water distribution. Can be electronically scheduled based on evapotranspiration (ET). App is available: (Morgan et al.)

26 Irrigation Advantages of drip irrigation: Smaller amounts of water reduced run-off and percolation. Increased water use efficiency. Fewer weeds. Advantages of microsprinklers: Provide a greater degree of frost-protection. Covers a larger area of the root zone.

27 Irrigation Drip irrigation Micro-sprinklers

28 Irrigation Test your irrigation water. High alkaline water (due to high carbonate, bicarbonate and hydroxyl anions) is detrimental to Citrus. If water has high alkalinity, neutralize by adding acid to the irrigation water. Citrus performs best at a soil ph of 6.0 to 6.5.

29 Nutrition

30 Nutrition Proper nutrition improves tolerance to pests and diseases. The primary goal during the first years is the rapid growth of the canopy to ensure fruit production.

31 Nutrition Optimal fertilizer rates depend on soil type: Soils with high organic matter will require less fertilizer than soils with low organic matter. Optimal rates also depend on land history: Land previously used for pasture or vegetable production will need less fertilizer than an established citrus grove. Test soil to assess nutritional needs.

32 Nutrition Fertilizer can be applied as dry material or through fertigation. To maintain constant nutrient availability and to avoid nutrient leaching, supply young trees with regular small doses of fertilizers.

33 Nutrition Ideally: Ten or more annual applications through fertigation. Alternatively: A minimum of 4-6 annual applications of dry soluble fertilizer. One or two applications of controlled released fertilizer (CRF). Can be applied pre-planting, incorporated after planting or broadcast.

34 Nutrition Lower limit of annual application frequency Year in grove Lbs N/ tree/year (range) Controlled release fertilizer Dry soluble fertilizer Fertigation Obreza, Morgan, Albrigo, Boman (2011)

35 Nutrition Additional foliar nutritional applications of micronutrients are very effective. Foliar sprays of micronutrients are quicker and more effective than soil applications. Test leaves to assess need for micronutrients.

36 Open Hydroponic Systems (OHS) ACPS Enhancing citrus production by optimizing daily water and nutrient levels. Daily irrigation. Daily fertigation (drip). Computerized monitoring. Remotely controlled. High planting density. Schumann, Syvertsen, Morgan (2009)

37 Organic amendments

38 Organic amendments Beneficial bacteria (PGPR) Beneficial fungi (AMF) Humic substances Seaweed extracts

39 Organic amendments Improve soil physicochemical properties. Enhance nutrient uptake and nutrient use efficiency. Enhance water use efficiency. Improve root architecture. Induce systemic resistance. Enhance tolerance to pathogens and diseases. Enhance tolerance to abiotic stresses.

40 Weed management

41 Weed management Weeds compete with young trees for water, nutrients and sunlight. Weeds should be controlled: 1) Pre-plant 2) Early post-plant 3) After tree is established If using residual herbicides, allow enough time for residues to disappear before planting.

42 Weed management Adjust herbicide applications to rates recommended for young trees. Avoid damage to young leaves. Protect trees from herbicide damage by using tree wraps. Balance herbicides use with the necessity to maintain a healthy root/soil environment.

43 Pest and disease control

44 Pest/disease control Young trees flush frequently and are therefore more attractive to pests, especially leafminers and psyllids. Both cause major leaf damage and spread canker and HLB, respectively.

45 Pest/disease control Young trees need to be protected for about 4 years to grow optimally. Best control is through use of soilapplied neonicotinoids. Soil applied products have less impact on beneficials. Soil drench is better than injection to the irrigation system to avoid losses of material outside the root zone.

46 Pest/disease control Currently 3 neonicotinoid products are registered for use in young trees: 1. Admire Pro (imidacloprid) 2. Platinum (thiamethoxam) 3. Belay (clothianidin) Apply about 2 weeks prior to leaf expansion to ensure movement from roots to shoot.

47 Pest/disease control Recommended rate per acre (fl oz) Product New reset (2-3 height) 1-2 years (3-5 height) 3-5 years (5-9 height) Admire Pro 4.6F Platinum 75 SG Belay Based on 140 trees/acre Single application

48 Trees/acre Pest/disease control No of applications possible at recommended rates for new resets (2-3 height) Admire Pro Platinum Belay Total

49 Trees/acre Pest/disease control No of applications possible at recommended rates for 1-2 year-old trees (3-5 height) Admire Pro Platinum Belay Total

50 Trees/acre Pest/disease control No of applications possible at recommended rates for 3-5 year-old trees (5-9 height) Admire Pro Platinum Belay Total

51 Pest/disease control Apply neonicotinoids to moist soil and follow with ~ 0.25 inches of irrigation. Avoid application 24 hours prior to rainfall or scheduled irrigation to avoid leaching past the root zone. Neonicotinoids may provide 6-8 weeks of protection. Presence of new leafminer damage indicates the need to reapply.

52 Pest/disease control All three insecticides have the same mode of action (IRAC Group 4A). Use foliar sprays of other (broad-spectrum) insecticides between soil applications to avoid insecticide resistance. Foliar sprays are most effective when used before new flush emerges.

53 Tree size Reset (<3 ) 1-2 yr (3-5 ) 3-5 yr (5-9 ) Pest/disease control Season-long ACP control A = Admire, P = Platinum, B = Belay Rogers (2014) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec P A A B B A A P P A B B B B A P P A B A B Foliar applications of insecticides are shown in orange.

54 Other Strategies

55 Metalized mulch

56 Metalized mulch Advantages: Psyllid repellence. More light. Less weeds. More efficient use of water, fertilizer, herbicides, and systemic pesticides. Higher soil and canopy temperatures.

57 Boxes per acre Metalized mulch Average boxes per acre 3 ½ years after planting Check Mulch Insectide Insectide + Mulch 44% % higher yields using mulch in combination with insecticides compared with insecticides alone. Croxton and Stansly (2014)

58 Metalized mulch Disadvantages: Need for dual irrigation system (drip and micro-sprinkler for freeze control). Dependence on liquid fertilization during the duration of the mulch (3 years).

59 Good management Disease control Accelerated production Earlier economic returns

60 Young_Tree_Care.pdf