Botrytis species are generally considered to be aggressive, necrotrophic plant pathogens. By contrast to this general perception, however, Botrytis species could frequently be isolated from the interior of multiple tissues in apparently healthy hosts of many species. Infection frequencies reached 50% of samples or more, but were commonly less, and cryptic infections were rare or absent in some plant species. Prevalence varied substantially from year to year and from tissue to tissue, but some host species routinely had high prevalence. The same genotype was found to occur throughout a host, representing mycelial spread. Botrytis cinerea and Botrytis pseudocinerea are the species that most commonly occur as cryptic infections, but phylogenetically distant isolates of Botrytis were also detected, one of which does not correspond to previously described species. Sporulation and visible damage occurred only when infected tissues were stressed, or became mature or senescent. There was no evidence of cryptic infection having a deleterious effect on growth of the host, and prevalence was probably greater in plants grown in high light conditions. Isolates from cryptic infections were often capable of causing disease (to varying extents) when spore suspensions were inoculated onto their own host as well as on distinct host species, arguing against co-adaptation between cryptic isolates and their hosts. These data collectively suggest that several Botrytis species, including the most notorious pathogenic species, exist frequently in cryptic form to an extent that has thus far largely been neglected, and do not need to cause disease on healthy hosts in order to complete their life-cycles.

<p>Kendala utama budidaya tanaman buah naga di Indonesia adalah masalah penyakit. Ada beberapa jenis patogen yang menyerang tanaman buah naga, namun penyakit yang paling berbahaya dan sangat merugikan adalah penyakit bintik batang. Penelitian ini bertujuan  mengkarakterisasi gejala serangan dan mengidentifikasi penyebab penyakit bintik batang pada tanaman buah naga. Penelitian dilakukan di kebun petani di area endemik Padang Pariaman dan Solok serta laboratorium penyakit dan molekular Balitbu Tropika sejak tahun 2014 sampai 2016. Penelitian dilakukan dengan metode deskriptif dan pengujian laboratorium. Karakterisasi gejala serangan penyakit diamati  terhadap bagian tanaman yang terserang. Identifikasi dilakukan dengan pengamatan cendawan penyebab penyakit secara mikroskopis, uji postulat Koch dan uji DNA. Hasil penelitian menunjukkan bahwa gejala awal penyakit ditandai dengan adanya bintik kecil berwarna putih pada tunas muda dan buah  tanaman buah naga, ditengah bintik ditemukan lubang halus seperti tusukan jarum. Gejala lebih lanjut berupa bercak-bercak yang sedikit membesar, menyatu dan bagian batang yang lunak berlubang dan hancur. Berdasarkan ciri-ciri mikroskopis dan hasil amplifikasi region ITS DNA isolat cendawan asal buah naga teramplifikasi pada 580 bp dan berdasarkan identifikasi bank gen (BLAST), sekuen nukleotida isolat cendawan menunjukkan 99% kesamaan dengan <em>Neoscytalidium dimidiatum</em>. Hasil penelitian ini selanjutnya dapat menjadi dasar/rujukan dalam melakukan penelitian untuk mencari teknik pengendalian di lapangan nantinya.</p><p>Kendala utama budidaya tanaman buah naga di Indonesia adalah masalah penyakit. Ada beberapa jenis patogen yang menyerang tanaman buah naga, namun penyakit yang paling berbahaya dan sangat merugikan adalah penyakit bintik batang. Penelitian ini bertujuan  mengkarakterisasi gejala serangan dan mengidentifikasi penyebab penyakit bintik batang pada tanaman buah naga. Penelitian dilakukan di kebun petani di area endemik Padang Pariaman dan Solok serta laboratorium penyakit dan molekular Balitbu Tropika sejak tahun 2014 sampai 2016. Penelitian dilakukan dengan metode deskriptif dan pengujian laboratorium. Karakterisasi gejala serangan penyakit diamati  terhadap bagian tanaman yang terserang. Identifikasi dilakukan dengan pengamatan cendawan penyebab penyakit secara mikroskopis, uji postulat Koch dan uji DNA. Hasil penelitian menunjukkan bahwa gejala awal penyakit ditandai dengan adanya bintik kecil berwarna putih pada tunas muda dan buah  tanaman buah naga, ditengah bintik ditemukan lubang halus seperti tusukan jarum. Gejala lebih lanjut berupa bercak-bercak yang sedikit membesar, menyatu dan bagian batang yang lunak berlubang dan hancur. Berdasarkan ciri-ciri mikroskopis dan hasil amplifikasi region ITS DNA isolat cendawan asal buah naga teramplifikasi pada 580 bp dan berdasarkan identifikasi bank gen (BLAST), sekuen nukleotida isolat cendawan menunjukkan 99% kesamaan dengan <em>Neoscytalidium dimidiatum</em>. Hasil penelitian ini selanjutnya dapat menjadi dasar/rujukan dalam melakukan penelitian untuk mencari teknik pengendalian di lapangan nantinya.</p>

ABSTRAK. Minyak cengkeh dan cendawan Gliocladium sp. diketahui memiliki potensi sebagai agens pengendali cendawan Fusarium oxysporum f. sp. cubense (Foc), penyebab penyakit layu pada tanaman pisang. Pengujian kompatibilitas antara minyak cengkeh dengan cendawan Gliocladium sp. perlu dievaluasi dalam rangka menyusun paket pengendalian terpadu terhadap penyakit layu Fusarium. Tujuan penelitian ialah mengevaluasi pengaruh minyak cengkeh terhadap pertumbuhan koloni cendawan Gliocladium sp. dan daya hambatnya terhadap cendawan Foc ras 4. Penelitian dilaksanakan di Laboratorium Proteksi Tanaman Balai Penelitian Tanaman Buah Tropika pada bulan Mei sampai Juli 2008. Perlakuan terdiri atas minyak cengkeh volume 3, 9, dan 18 µl disusun dalam rancangan acak lengkap dengan lima ulangan. Hasil penelitian menunjukkan bahwa miselium cendawan Gliocladium sp. yang mendapat perlakuan minyak cengkeh masih mampu tumbuh hingga memenuhi ruang cawan petri. Jumlah konidia cendawan Gliocladium sp. yang diperlakukan dengan minyak cengkeh terbukti lebih sedikit dibanding cendawan yang tidak diperlakukan dengan minyak cengkeh. Cendawan Gliocladium sp. yang telah mendapat perlakuan minyak cengkeh masih memiliki sifat antagonistik yang efektif terhadap cendawan Foc. Efektivitas antagonisme cendawan tersebut tidak berbeda nyata dengan efektivitas antagonisme yang tidak diperlakukan dengan minyak cengkeh. Hasil ini memberikan harapan karena minyak cengkeh tidak memberikan efek negatif terhadap aktivitas Gliocladium sp., sehingga dapat dijadikan sebagai salah satu komponen dalam program pengendalian secara terpadu penyakit layu Fusarium pada pisang. Namun masih diperlukan penelitian lebih lanjut mengenai pengaruh minyak cengkeh terhadap pertumbuhan tanaman.Katakunci: Minyak atsiri cengkeh; Gliocladium sp.; Fusarium oxysporum f. sp. cubense; Antagonisme.

Scars on mangosteen fruits caused by thrips are the most prominent constraint in Indonesian export of mangosteen. Most of the exported mangosteen are rejected due to scar appearance. This research aimed to study the effects of fruit bagging, sanitation, and sticky trap application on the scar intensity on mangosteen. The research was conducted at a farmer's polycultured mangosteen orchard in Lima Puluh Kota, West Sumatra, Indonesia from September 2006 to February 2007. The mangosteen trees were cultured with cacao and coconut. To study the effects of bagging on the number of scars, the fruits were individually bagged at different time points starting from the time of calyx falling down (0) followed at 2, 4, 6, 8, 10, 12, and 14 weeks later. Each treatment was replicated six times. The experiment of sanitation (SNT) and yellow fluorescent sticky trap (YST) application was designed in a completely randomized design with six replications, except for the control which was replicated only three times. Four treatments studied were SNT, YST, combination of SNT+YST, and control. The sanitation was applied by removing all weeds under the canopy of mangosteen trees followed with soil tillage and fogging. The sticky trap was nailed on woody sticks and placed on 3 m above the ground at four different positions around the tree canopy. Parameters observed were the percentage and intensity of scars and number of thrips caught on the sticky traps. The results showed that application of early bagging, SNT, YST, and SNT+YST were effective to reduce intensity and percentage of scars. However, combination of SNT+YST demonstrated the best results in reducing the intensity and percentage of scars by 32.14% and 42.82%, respectively. Combination of SNT+YST also drastically decreased thrips population as indicated by the low number of thrips catched after five biweekly observations. Since the fifth observation, the thrips population was low (less than 5 thrips catched per sticky trap) and far below the economic threshold. The present study implies the importance of early fruit bagging, sanitation, and sticky trap application in protecting mangosteen fruits from scars.

Manganese (Mn) is one of the essential micronutrients that plays a crucial role in plants' growth and development and is also considered a limiting factor for crop production. This study aimed to determine the critical level of Mn in soil and leaves for improving the quality of mangosteen fruit. The research was conducted in 2015 in several mangosteen production centers, including West Sumatra (Simalanggang and Banja Laweh), West Java (Karacak and Barengkok), Bali (Belimbing and Selamadeg). A well-maintained of fifteen to twenty years old mangosteen plants were used with uniform soil fertility. Purposive random sampling is conducted in each location to select ten plants from each site. Soil samples are taken from under the plant canopy around 0-30 cm in depth at the four cardinal directions. The terminal leaves that collected from the middle part of the plant canopy are used as the leaf samples. Physiological ripe fruits are taken after ripening with index 3-4. The parameters observed consist of (1) soil pH of H2O, Ca, Mg, Mn-available, (2) levels of Mn, Ca, Mg, and K in the leaves, (3) fruit quality (fruit weight, fruit diameter, fruit skin thickness, aryl weight, seed weight). The results showed the Mn content in the soil ranged from 18.89 to 33.63 ppm. Available Mn is negatively affected by pH, Ca, and Mg exchangeability. Soil Mn is linearly related to leaf Mn with R2 0.76. The critical values of Mn in leaf and soil for mangosteen plants in Indonesia were 425 ppm and 22 to 24 ppm, respectively.